Liquid crystal mixtures and devices

ABSTRACT

The invention describes liquid crystal compounds of formula (I) which are suitable for use in liquid crystal devices including those devices which exploit the electroclinic effect, ##STR1## where X may be CN, NO 2 , CF 3 , CF 2  H, CFH 2 , halogen, hydrogen, alkyl or alkoxy; X 2  may be CN, NO 2 , CF 3 , CF 2  H, CFH 2 , halogen, hydrogen, alkyl or alkoxy; X 3  may be CN, NO 2 , CF 3 , CF 2  H, CFH 2 , halogen, alkyl, alkoxy or hydrogen; X 4  may be CN, NO 2 , CF 3 , CF 2  H, CFH 2 , halogen, alkyl, alkoxy or hydrogen; provided that at lease one of X or X 2  is CF 3 , CF 2  H, CFH 2 , CN, NO 2  or halogen; A and B are independently phenyl, mono-fluorinated phenyl, di-fluorinated phenyl or cyclohexyl; Y may be single bond, COO, OOC, C═C; q may be 0 or 1; R 1  may be an end group of formula (II) wherein Z may be a single bond, O, CO 2 , (CH 2 ) n  or (CH 2 ) n  O where n may be 1 or 2; J and M may be independently H, C 1-4  alkyl; W may be C 1  -C 12  straight or branched alkyl chain; R 2  may contain 1-14 carbon atoms wherein one or more non-adjacent CH 2  groups may be replaced by CO 2  or O. X or X 2  may give rise to steric hindrance with the nearest terminal group. The materials of the current invention may be mixed together and/or with other liquid crystal compounds. Suitable devices which the materials of the present invention may be incorporated in include beam steerers, piezoelectric actuators or sensors and pyroelectric sensors and displays in general. The materials of the present invention may also be useful as dopants in ferroelectrics and as second order non-linear optic materials for second harmonic conversion of light.

This application is a 371 application of PCT/GB95/00018.

This application is a 371 application of PCT/GB95/00018.

This invention relates to liquid crystal materials, in particular it relates to liquid crystal materials which exhibit one or more smectic phases.

Liquid crystals can exist in various phases. In essence there are three different classes of liquid crystalline material, each possessing a characteristic molecular arrangement. These classes are nematic, cholesteric and smectic. A wide range of smectic phases exists, for example smectic A and smectic C. Some liquid crystal materials possess a number of liquid crystal phases on varying the temperature, others have just one phase. For example, a liquid crystal material may show the following phases on being cooled from the isotropic phase:--isotropic--nematic--smectic A--smectic C--solid. If a material is described as being smectic A then it means that the material possesses a smectic A phase over a useful working temperature range.

Materials possessing a smectic A*(S_(A) *) phase may exhibit an electroclinic effect. The electroclinic effect was first described by S. Garoff and R. Meyer, Phys. Rev. Lett., 38, 848 (1977). An electroclinic device has also been described in UK patent application GB 2 244 566 A. This particular device helps to overcome the poor alignment problems of electroclinic (EC) devices using a surface alignment that gives a surface tilt within a small range of angles.

When a smectic A phase is composed of chiral molecules, it may exhibit an electroclinic effect, ie a direct coupling of molecular tilt to applied field. The origin of the electroclinic effect in a smectic A* phase composed of chiral polar molecules has been described by Garoff and Meyer as follows. The application of an electric field parallel to the smectic layers of such a smectic A* phase biases the free rotation of the transverse molecular dipoles and therefore produces a non-zero average of the transverse component of the molecular polarization. When such a dipole moment is present and coupled to the molecular chirality, a tilt of the long molecular axis (the director) is induced in a plane perpendicular to the dipole moment.

In thin samples for example 1-3 μm and with the smectic layers tilted or perpendicular with respect to the glass plates the electroclinic effect is detectable at low applied fields.

In an aligned smectic A sample a tilt of the director is directly related to a tilt of the optic axis. The electroclinic effect results in a linear electro-optic response. The electro-optic effect can manifest itself as a modulation of the effective birefringence of the device.

Electroclinic devices are useful, for example, in spatial light modulators having an output that varies linearly with applied voltage. A further advantage of EC devices is that they have high speed response times, much faster than nematic based devices, including twisted nematic based devices. Unlike ferroelectric devices the EC device is not bistable.

The electroclinic effect is sometimes referred to as the soft-mode effect see G. Andersson et at in Appl. Phys. Lett., 51, 9, (1987).

In general terms, regarding the electroclinic effect, it is advantageous if on applying a small voltage there results a large induced tilt.

An increase in induced tilt may result in an increase in contrast ratio or in phase modulation depth.

It is also advantageous if a large induced tilt can be obtained at as low a voltage as possible.

It is also advantageous if the relationship between molecular induced tilt and applied voltage is temperature independent. When an increase in applied voltage results in little or no change in induced tilt then the material being tested is generally referred to as exhibiting a saturation voltage effect.

Wand et al in Abstracts of the 4^(th) International Conference of Ferroelectric Liquid Crystals Sep. 28-Oct. 1, 1993 in Tokyo, Japan: Paper P90, pages 257-58 and see references therein, report on novel electroclinic materials. They suggest that the reason for the materials they report exhibiting a large and temperature insensitive electroclinic tilt is due to the absence of a C* phase underlying the A* phase and that it is usual for materials possessing a C* phase below the A* phase to exhibit a relatively steep temperature dependence of induced tilt.

By S_(A) * is meant a S_(A) phase which contains some proportion of chiral molecules.

According to this invention an electroclinic device comprises two spaced cell walls each bearing electrode structures and treated on at least one facing surface with an alignment layer, a layer of a smectic liquid crystal material enclosed between the cell walls, characterised in that the liquid crystal material contains one or more of the compounds described by formula I: ##STR2## wherein X may be CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy;

X₂ may be CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy;

X₃ may be CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy or hydrogen;

X₄ may be CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy or hydrogen;

provided that at least one of X or X₂ is CF₃, CF₂ H, CFH₂, CN, NO₂ or halogen;

A and B are independently phenyl, mono-fluorinated phenyl, di-fluorinated phenyl or cyclohexyl;

Y may be single bond, COO, OOC, C═C;

q may be 0 or 1;

R₁ may be an end group of the following Formula II: ##STR3## wherein Z may be a single bond, O, CO₂, (CH₂)_(n) or (CH₂)_(n) O where n may be 1 or 2;

J and M may be independently H, C₁₋₄ alkyl;

W may be C₁ -C₁₂ straight or branched alkyl chain;

R₂ may contain 1-14 carbon atoms wherein one or more non-adjacent CH₂ groups may be replaced by CO₂ or O.

Preferably:

W is C₁ -C₈ straight chain alkyl, Z is O or CH₂ O, M or J are independently chosen from H or Me or Et;

R₂ contains 5-12 carbon atoms wherein one of the CH₂ groups may be replaced by CO₂ or O;

q=1;

A and B are both phenyl;

X₃ and X₄ are both H;

Y is CO₂ or a single bond;

X or X₂ is NO₂ or CF₃ or halogen or CN.

According to a second aspect of this invention compounds of the following formula are provided: ##STR4## wherein X may be CF₃, CF₂ H, CFH₂, hydrogen, NO₂, alkyl or alkoxy;

X₂ may be CF₃, CF₂ H, CFH₂, hydrogen, NO₂, alkyl or alkoxy;

X₃ may be CF₃, CF₂ H, CFH₂, alkyl, NO₂, alkoxy or hydrogen;

X₄ may be CF₃, CF₂ H, CFH₂, alkyl, NO₂, alkoxy or hydrogen;

provided that at least one of X or X₂ is CF₃, CF₂ H, CFH₂, NO₂ ;

A and B are independently phenyl, mono-fluorinated phenyl, di-fluorinated phenyl or cyclohexyl;

Y may be single bond, COO, OOC, C═C;

q may be 0 or 1;

R₁ may be an end group of the following Formula II: ##STR5## wherein Z may be a single bond, O, CO₂, (CH₂)_(n) or (CH₂)_(n) O where n may be 1 or 2;

J and M may be independently H, C₁₋₄ alkyl;

W may be C₁ -C₁₂ straight or branched alkyl chain;

R₂ may contain 1-14 carbon atoms wherein one or more non-adjacent CH₂ groups may be replaced by CO₂ or O.

Preferably:

W is C₁ -C₈ straight chain alkyl, Z is O or CH₂ O, M or J are independently chosen from H or Me or Et;

R₂ contains 5-12 carbon atoms wherein one of the CH₂ groups may be replaced by CO₂ or O;

q=1;

A and B are both phenyl;

X₃ and X₄ are both H;

Y is CO₂ or a single bond;

X or X₂ is CF₃.

It is believed that these compounds may be characterised by there being intramolecular steric hindrance between the `X` group(s) and the adjacent terminal groups of formula I. This in turn may induce a large incipient spontaneous polarisation (Ps) in the molecule which in turn gives rise to a large induced tilt when a field is applied. A large induced tilt usually gives rise to an improved contrast ratio.

The invention will now be described, by way of example only, with reference to the following diagrams.

FIGS. 1-18 show synthetic schemes for the preparation of compounds.

FIGS. 19A and 19B illustrate front and sectional views respectively of a reflective spatial light modulator drawn to different scales, in which the materials of the current invention may be incorporated.

FIG. 20 is a graph of tilt angle/° versus applied voltage/V over a range of temperatures for compound 18.

FIG. 21 is a graph of tilt angle/° versus applied voltage/V over a range of temperatures for compound 60.

FIG. 22 is a graph of tilt angle/° versus applied voltage/V over a range of temperatures for compound 70.

Reagents used in the synthetic route of FIG. 1 are shown in the corresponding Scheme 1.

1a: H₂ SO₄, H₂ O, HOAc

1b: HBr, HOAc

1c: (i) MeOCOCl, NaOH, H₂ O; (ii) aq. HCl

1d: octan-1-ol, DEAD, PPh₃, THF

1e: aq NH₃, EtOH

Reagents used in the synthetic route of FIG. 2 are shown in the corresponding Scheme 2.

2a: R*OH, DEAD, PPh₃, THF

2b: (i) NaOH, H₂ O, EtOH; (ii) aq HCl

2c: HNO₃, H₂ SO₄, glacial acetic acid

2d: DCC, DMAP, CH₂ Cl₂

Reagents used in the synthetic route of FIG. 3 are shown in the corresponding Scheme 3.

3a: (i) MeOCOCl, NaOH, H₂ O; (ii) aq. HCl

3b: octan-1-ol or decan-1-ol, DEAD, PPh₃, THF

3c: aq. NH₃, EtOH

Reagents used in the synthetic route of FIG. 4 are shown in the corresponding Scheme 4.

4a: H₂ SO₄, H₂ O, glacial acetic acid

4b: H₂ SO₄, HNO₃, glacial acetic acid

4c: DCC, DMAP, CH₂ Cl₂

Reagents used in the synthetic route of FIG. 5 are shown in the corresponding Scheme 5.

5a: (i) MeOCOCl, NaOH, H₂ O; (ii) aq. HCl

5b: DEAD, PPh₃, THF

5c: (S)-nonan-3-ol, DEAD/PPh₃, THF

Reagents used in the synthetic route of FIG. 6 are shown in the corresponding Scheme 6.

6a: DCC, DMAP, CH₂ Cl₂

Reagents used in the synthetic route of FIG. 7 are shown in the corresponding Scheme 7.

7a: (S)-octan-2-ol, DEAD, PPh₃, THF

7b: (i) n-butyllithium, THF, (ii) CO₂ (solid), THF; (iii) aq. HCl

7c: DCC, DMAP, CH₂ Cl₂

Reagents used in the synthetic route of FIG. 8 are shown in the corresponding Scheme 8.

8a: R*OH, DEAD, PPh₃, THF

8b: Br₂, CHCl₃

8c: (i) n-butyllithium, THF, (ii) CO₂ (solid), THF; (iii) aq. HCl

8d: DCC, DMAP, CH₂ Cl₂

8e: (i) n-butyllithium, THF, (ii) trimethyl borate, THF; (iii) aq. HCl

8f: H₂ O₂, THF

Reagents used in the synthetic route of FIG. 9 are shown in the corresponding Scheme 9.

9a: (S)-octan-2-ol, DEAD, PPh₃, THF

9b: Br₂, CHCl₃

9c: (i) n-butyllithium, THF, (ii) CO₂ (solid), THF; (iii) aq. HCl

9d: DCC, DMAP, CH₂ Cl₂

Reagents used in the synthetic route of FIG. 10 are shown in the corresponding Scheme 10.

10a: 1-bromodecane, K₂ CO₃, KI, butanone

10b: H₂ SO₄, H₂ O, glacial acetic acid

10c: DCC, DMAP, CH₂ Cl₂

Reagents used in the synthetic route of FIG. 11 are shown in the corresponding Scheme 11.

11a: (S)-2-methylbutan-1-ol or (S)-octan-2-ol, DEAD/PPh₃, THF

11b: Br₂, CHCl₃

Reagents used in the synthetic route of FIG. 12 are shown in the corresponding Scheme 12.

12a: (S)-octan-2-ol, DEAD, PPh₃, THF

12b: (i) n-butyllithium, THF or Mg, THF; (ii) CO₂ (solid), THF; (iii) aq. HCl

12c: Pd(PPh₃)₄, 2M NaCO₃, 1,2-dimethoxyethane

Reagents used in the synthetic route of FIG. 13 are shown in the corresponding Scheme 13.

13a: 2-methyl-but-3-yn-2-ol, Pd(PPh₃)₄, CuI, diisopropylamine

13b: NaOH, toluene

13c: Pd(PPh₃)₄, CuI, triethylamine

Reagents used in the synthetic route of FIG. 14 are shown in the corresponding Scheme 14.

14a: H₂ O, HNO₃, glacial acetic acid

14b: (S)-octan-2-ol, DEAD, PPh₃, THF

14c: Br₂, CHCl₃

14d: Pd(PPh₃)⁴, 2M NaCO₃, 1,2-dimethoxyethane

Reagents used in the synthetic route of FIG. 15 are shown in the corresponding Scheme 15.

15a: 1-bromooctane, K₂ CO₃, KI, butanone

15b: (i) n-butyllithium, THF, (ii) trimethyl borate, THF; (iii) aq. HCl

15c: Pd(PPh₃)₄, 2M NaCO₃, 1,2-dimethoxyethane

Reagents used in the synthetic route of FIG. 16 are shown in the corresponding Scheme 16.

16a: DCC, DMAP, CH₂ Cl₂

Reagents used in the synthetic route of FIG. 17 are shown in the corresponding Scheme 17.

17a: 1-bromooctane, K₂ CO₃, KI, butanone

17b: (i) NaOH, H₂ O, EtOH (ii) aq HCl

17c: DCC, DMAP, CH₂ Cl₂

Reagents used in the synthetic route of FIG. 18 are shown in the corresponding Scheme 18.

18a: octan-2-ol, DEAD, TPP, THF;

18b: Br₂, CHCl₃ ;

18c: (i) Mg, THF; (ii) (MeO)₃ B, THF; (iii) 10% HCl;

18d: Pd(PPh₃)₄, DME, Na₂ CO₃, water.

where:

DEAD=diethylazodicarboxylate,

THF=tetrahydrofuran,

DCC=dicyclohexylcarbodiimide,

DMAP=N,N-dimethylaminopyridine,

TPP=triphenylphosphine,

DME=1,2-dimethoxyethane.

Experimental details relating to the steps in synthetic schemes described by FIGS. 1-18 are as follows.

4'-Methoxy-4-biphenylcarboxylic acid (2)

A stirred mixture of 4-cyano-4'-methoxybiphenyl (1) (30.00 g, 0.144 mol), concentrated sulphuric acid (60 ml), and water (60 ml) in glacial acetic acid (600 ml) was heated under reflux for 6 h. The mixture was left to cool to room temperature, during which time white crystals formed, and then poured into an ice/water mixture (2 l). The resultant white precipitate was filtered off and washed with water until acid-free. The white solid was recrystallised from glacial acetic acid to afford colourless crystals which were dried over potassium hydroxide in vacuo.

TLC analysis (5% methanol/dichloromethane) revealed two spots.

Yield 27.50 g (84%); mesomorphic behaviour (°C.) K 254.6N 295 I (lit. K 258N 300 I).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3  + DMSO) δ                    3.85(3H, s), 7.00(2H, d), 7.60(2H, d),                    7.65(2H, d), 8.10(2H, d), no obvious                    OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                    3300-2300, 1680, 1255, 930;     MS (m/z)       228 M.sup.+ !, 213, 185, 139.     ______________________________________

4'-Hydroxy-4-biphenylcarboxylic acid (3)

A stirred mixture of compound 2 (27.00 g, 0.118 mol) and hydrobromic acid (48% w/v, 350 ml) in glacial acetic acid (600 ml) was heated under reflux for 6 h. The cooled solution was poured into an ice/water mixture (1 l) and the resulting white precipitate was filtered off and washed with water until acid-free. Recrystallisation from glacial acetic acid afforded white crystals which were dried over potassium hydroxide in vacuo.

Yield 20.00 g (79%); mp >300° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3  + DMSO) δ                    6.95(2H, d), 7.50(2H, d), 7.60(2H, d),                    8.05(2H, d), no obvious OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                    3700-2300, 1680, 940;     MS (m/z)       214 M.sup.+ !, 196, 168, 70, 58.     ______________________________________

4'-Methoxycarbonyloxy-4-biphenylcarboxylic acid (4)

Methyl chloroformate (12.90 g, 0.137 mol) was added dropwise, over 10 minutes, to a stirred, cooled (5° C.) solution of compound 3 (10.00 g, 0.047 mol) in sodium hydroxide (5.44 g, 0.136 mol) and water (150 ml). During the addition a white precipitate was formed and this stirred mixture was allowed to warm to room temperature overnight. The resultant mixture was carefully acidified (pH 5) with dilute hydrochloric acid and the resultant voluminous white solid was filtered off, washed with water until acid-free and dried (phosphorus pentoxide) in vacuo.

Yield 11.87 g (93%); mesomorphic behaviour (°C.) K 253N 300<I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3  + DMSO) δ                    3.95(3H, s), 7.30(2H, d), 7.65(2H, d),                    7.65(2H, d), 8.10(2H, d), no obvious                    OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                    3300-2300, 1760, 1670, 1260, 930;     MS (m/z)       272 M.sup.+ !, 228, 213, 185, 139, 59.     ______________________________________

Octyl4'-methoxycarbonyloxy-4-biphenylcarboxylate (5)

A solution of triphenylphosphine (3.78 g, 0.014 mol) in dry tetrahydrofuran (50 ml) was added to a stirred solution of compound 4 (3.92 g, 0.014 mol), octan-1-ol (1.88 g, 0.014 mol) and diethyl azodicarboxylate (DEAD) (2.51 g, 0.014 mol) in dry tetrahydrofuran (100 ml) under an atmosphere of dry nitrogen. The addition was such that the triphenylphosphine was added over 30 seconds in which time the solution became hot and the white solid (4) and orange colour (DEAD) disappeared. The resultant solution was stirred overnight, the solvent was removed in vacuo and the viscous, oily residue was purified by column chromatography (10% petrol/dichloromethane) to give a colourless solid which was recrystallised from ethanol to leave colourless plates.

Yield 5.30 g (99%); mp 46°-47° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.20-1.55(10H, m), 1.70-1.85(2H, m),                3.95(3H, s), 4.35(2H, t), 7.30(2H, d), 7.65(2H, d),                7,65(2H, d), 8.10(2H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1760, 1710, 1230;     MS (m/z)   384 M.sup.+ !, 272, 228, 139, 69, 57.     ______________________________________

Ocryl4'-hydroxy-4-biphenylcarboxylate (6)

A solution of compound 5 (5.25 g, 0.014 mol) and aqueous ammonia (35% w/v, 100 ml) in ethanol (200 ml) was stirred for 1 h at room temperature. TLC analysis (dichloromethane) revealed a complete reaction. The solvent was removed in vacuo and the white solid was recrystallised from ethanol to give colourless crystals.

Yield 4.48 g (99%); mp 98.5°-100° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                 0.90(3H, t), 1.20-1.55(10H, m), 1.80(2H, m),                 4.35(2H, t), 5.05-5.25(1H, s), 6.95(2H, d),                 7.55(2H, d), 7.65(2H, d), 8.05(2H, d);     IR (KBr) ν.sub.max /cm.sup.-1                 3600-3100, 1675;     MS (m/z)    326 M.sup.+ !, 214, 197, 147, 82, 69.     ______________________________________

(S)-(+)-Ethyl 4-(2-methylbutyloxy)benzoate (8)

Quantities: (S)-(-)-2-methylbutan-1-ol (5.00 g, 0.057 mol), ethyl 4-hydroxybenzoate (7) (9.47 g, 0.057 mol), DEAD (9.93 g, 0.057 mol), triphenylphosphine (14.95 g, 0.057 mol).

The experimental procedure was as described for the preparation of compound 5. The crude product was purified by column chromatography (10% petrol/dichloromethane) to give a colourless oil.

Yield 12.64 g (94%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.95(3H, t), 1.00(3H, d), 1.30(1H, m), 1.40(3H, t),                1.50-1.65(1H, m), 1.80-2.00(1H, m), 4.35(2H, m),                4.35(2H, q), 6.90(2H, d), 8.00(2H, d);     IR (neat) ν.sub.max /cm.sup.-1                1715, 1255;     MS (m/z)   236 M.sup.+ !, 166, 138, 121;     OR          α!.sub.D.sup.23° +10.3°(c=0.04,                CHCl.sub.3).     ______________________________________

(S)-(+)-4-(2-Methylbutyloxy)benzoic acid (9)

A mixture of compound 8 (10.40 g, 0.04 mol), sodium hydroxide (11.67 g, 0.208 mol), water (23 ml) and ethanol (225 ml) was heated under reflux for 2 h. The solution was allowed to cool, to room temperature, and then acidified with dilute hydrochloric acid. The solvent was removed to leave a white solid which was dissolved in ether and washed successively with saturated sodium hydrogen carbonate solution (until no more effervescense was observed) and water. After drying the ether (MgSO₄), the solvent was removed in vacuo and the white solid was recrystallised from ethanol to yield colourless crystals.

Yield 7.70 g (84%); mp 108°-109° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.95(3H, t), 1.05(3H, d), 1.30(1H, m), 1.60(1H, m),                1.90(1H, m), 4.85(2H, m), 6.95(2H, d), 7.60(2H, d),                no obvious OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                3300-2300, 1675, 1260, 960;     MS (m/z)   208 M.sup.+ !, 138, 121, 70, 65, 55;     OR          α!.sub.D.sup.22.5° +11.9°(c=0.02,                CHCl.sub.3).     ______________________________________

(S)-(+)-Ethyl 4-(2-methylbutyloxy)-3-nitrobenzoate (11)

Quantities: (S)-(-)-2-methylbutan-1-ol (1.94 g, 0.022 mol), ethyl 4-hydroxy-3-nitrobenzoate (10) (4.64 g, 0.022 mol), DEAD (3.83 g, 0.022 mol), triphenylphosphine (5.77 g, 0.022 mol).

The experimental procedure was as described for the preparation of compound 5. The crude product was purified by column chromatography (10% petrol/dichloromethane) to leave a pale yellow solid.

Yield 5.75 g (93%); mp 66°-68° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.95(3H, t), 1.10(3H, d), 1.35(1H, m), 1.40(3H, t),                1.60(1H, m), 1.95(1H, m), 4.00(2H, m), 4.40(2H,                q), 7.10(1H, d), 8.20(1H, dd), 8.50(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1700, 1530, 1350, 1245;     MS (m/z)   281 M.sup.+ !, 212, 183, 166, 70;     OR          α!.sub.D.sup.23° +4.1°(c=0.02,                CHCl.sub.3).     ______________________________________

S-(+)-4-(2-Methylbutyloxy)-3-nitrobenzoic acid (12)

Method 1

Compound 9 (4.00 g, 0.02 mol) was dissolved in hot glacial acetic acid (20 ml) and the resultant stirred solution was cooled to 5° C. A solution of concentrated sulphuric acid (12 ml) in glacial acetic acid (20 ml) was added, followed by the careful addition of a cooled (5° C.) solution of concentrated nitric acid (12 ml) and concentrated sulphuric acid (12 ml) in glacial acetic acid (20 ml). The mixture was then allowed to warm to 20° C. for 1 h and the resultant yellow solution was poured into an ice-water mixture (300 ml). The pale-yellow solid was filtered off, washed with water until acid-free and recrystallised from ethanol to give pale-yellow crystals.

Yield 3.45 g (72%); mp 177°-178° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3  + DMSO) δ                    0.95(3H, t), 1.05(3H, d), 1.35(1H, m),                    1.60(1H, m), 1.95(1H, m), 4.00(2H, m),                    7.15(1H, d), 8.20(1H, dd), 8.50(1H, d), no                    obvious OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                    3300-2400, 1705, 1530, 1350, 1250, 915;     MS (m/z)       253 M.sup.+ !, 183, 166, 138, 70;     OR              α!.sub.D.sup.20° +10.6°(c=0.02,     ______________________________________                    DMF).

(S)-(+)-4-(2-Methylbutyloxy)-3-nitrobenzoic acid (12)

Method 2

Quantities: compound 11 (2.00 g, 7.12 mmol), sodium hydroxide 0.6 g, 0.015 mol), ethanol (80 ml), water (20 ml).

The experimental procedure was as described for the preparation of compound 9.

Yield 1.77 g (98%).

Spectra as for method 1.

(R)-(-)-Ethyl 4-(1-methylheptyloxy)benzoate (13)

Quantities: Ethyl 4-hydroxybenzoate (7) (3.83 g, 0.023 mol), (S)-(+)-octan-2-ol (3.00 g, 0.023 mol), DEAD (4.01 g, 0.023 mol), triphenylphosphine (6.04 g, 0.023 mol).

The experimental procedure was as described for the preparation of compound 5. The crude product was purified by column chromatography (10% petrol/dichloromethane) to give a colourless oil.

Yield 5.81 g (91%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.30(3H, d), 1.35(3H, t), 1.20-1.50(8H,                m), 1.50-1.85(2H, m), 4.35(2H, q), 4.45(1H, m),                6.90(2H, d), 8.00(2H, d);     IR (neat) ν.sub.max /cm.sup.-1                1710, 1250;     MS (m/z)   278 M.sup.+ !, 166, 138, 121;     OR          α!.sub.D.sup.23° -10.2°(c=0.03,                CHCl.sub.3).     ______________________________________

(R)-(-)-4-(1-Methylheptyloxy)benzoic acid (14)

Quantities: compound 13 (4.00 g, 0.014 mol), sodium hydroxide (1.15 g, 0.029 mol), ethanol (80 ml), water (20 ml).

The experimental procedure was as described for the preparation of compound 9. The product was recrystallised from ethanol to give colourless crystals.

Yield 3.36 g (96%); mp 61°-63° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.30(3H, d), 1.15-1.50(8H, m), 1.50-                1.65(1H, m), 1.65-1.85(1H, m), 4.45(1H, m),                6.90(2H, d), 8.05(2H, d), no obvious OH                absorption;     IR (KBr) ν.sub.max /cm.sup.-1                3200-2300, 1680, 1260, 945;     MS (m/z)   250 M.sup.+ !, 138, 121;     OR          α!.sub.D.sup.23° -9.6°(c=0.06,                CHCl.sub.3).     ______________________________________

(R)-(-)-Ethyl 4-(1-methylheptyloxy)-3-nitrobenzoate (15)

Quantities: Ethyl 4-hydroxy-3-nitrobenzoate (10) (4.85 g, 0.023 mol), (S)-(+)-octan-2-ol (3.00 g, 0.023 mol), DEAD (4.01 g, 0.023 mol), triphenylphosphine (6.03 g, 0.023 mol).

The experimental procedure was as described for the preparation of compound 5 but the reaction mixture was left stirring for 4 days. The crude product was purified by column chromatography (10% petrol/dichloromethane) to give a pale yellow oil.

Yield 6.06 g (82%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)               0.90(3H, t), 1.00-1.20(8H, m), 1.40(3H, d),     δ   1.40(3H, t), 1.65(1H, m), 1.80(1H, m), 4.40(2H, q),               4.60(1H, m), 7.10(1H, d), 8.15(1H, dd), 8.45(1H, d);     IR(neat)  1725, 1540, 1370, 1245, 940;     ν.sub.max /cm.sup.-1     MS(m/z)   323 M.sup.+ !, 212, 183, 166, 112, 83, 70, 57;     OR         α!.sub.D.sup.23° -16.1°(c=0.05,               CHCl.sub.3).     ______________________________________

(R)-(-)-4-(1-Methylheptyloxy)-3-nitrobenzoic acid (16)

Quantities: compound 15 (5.00 g, 0.015 mol), sodium hydroxide (1.24 g, 0.031 mol), ethanol (160 ml), water (40 ml).

The experimental procedure was as described for the preparation of compound 9. The resultant solid was recrystallised from ethanol to give a pale, yellow solid.

Yield 4.38 g (99%); mp 64°-66° C.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)               0.90(3H, t), 1.40(3H, d), 1.20-1.60(8H, m),     δ   1.70(1H, m), 1.85(1H, m), 4.65(1H, m), 7.15(1H, d),               8.25(1H, dd), 8.50(1H, d);     IR(KBr)   3400-2300, 1700, 1540, 1355, 1260, 940;     ν.sub.max /cm.sup.-1     MS(m/z)   295 M.sup.+ !, 183, 166, 112, 83, 70, 57;     OR         α!.sub.D.sup.23° -13.9°(c=0.05,               CHCl.sub.3).     ______________________________________

(S)-(+)-Octyl 4'- 4-(2-methylbutyloxy)-3-nitrobenzoyloxy!-4-biphenylcarboxylate (17)

A solution of DCC (1.47 g, 7.12 mmol) and DMAP (0.08 g, 0.66 mmol) in dichloromethane (30 ml) was added to a stirred solution of compound 10 (1.50 g, 5.93 mmol) and compound 6 (1.93 g, 5.93 mmol) in dichloromethane (30 ml). The resultant solution was stirred overnight under dry conditions (CaCl₂) after which time the white precipitate (DCU) was filtered off and the solvent removed in vacuo. The residue was purified by column chromatography (10% petrol/dichloromethane) and recrystallised from ethanol to yield pale yellow crystals.

Yield 1.82 g (55%); mesomorphic behaviour (°C.) K 85.0 (S_(C) * 71.7) S_(A) * 126.8 I.

    ______________________________________     .sup.1 H NMR             0.90(3H, t), 0.95(3H, t), 1.05(3H, d), 1.15-1.60(11H, m),     (CDCl.sub.3)δ             1.60(1H, m), 1.80(2H, m), 2.00(1H, m), 4.05(2H, m),             4.35(2H, t), 7.20(1H, d), 7.30(2H, d), 7.70(2H, d),             7.70(2H, d), 8.10(2H, d), 8.35(1H, dd), 8.70(1H, d);     IR(KBr) 1740, 1725, 1540, 1355, 1235;     ν.sub.max /cm.sup.-1     MS(m/z) 561 M.sup.+ !, 326, 236, 166;     OR       α!.sub.D.sup.23° +2.2°(c=0.03,     ______________________________________             CHCl.sub.3).

(R)-(-)-Octyl 4'- 4-(1-methylheptyloxy)-3-nitrobenzoyloxy!-4-biphenylcarboxylate (18)

Quantities: compound 16 (2.00 g, 6.80 mmol), compound 6 (2.22 g, 6.80 mmol), DCC (1.68 g, 8.16 mmol), DMAP (0.10 g, 0.76 mmol).

The experimental procedure was as described for the preparation of compound 17. The crude product was purified by column chromatography (10% petrol/dichloromethane) and recrystallised from ethanol. The ethanol solution was cooled rapidly from boiling (78° C.) with liquid nitrogen and then left at -20° C. overnight to give a sticky, pale yellow solid.

Yield 1.49 g (36%); mesomorphic behaviour (°C.) K 37.0 S_(C) * 56.4 S_(A) * 62.5 I.

    ______________________________________     .sup.1 H NMR             0.90(3H, t), 0.90(3H, t), 1.40(3H, d), 1.20-1.60(18H, m),     (CDCl.sub.3)δ             1.60-1.95(4H, m), 4.35(2H, t), 4.65(1H, m), 7.20(1H, d),             7.30(2H, d), 7.65(2H, d), 7.70(2H, d), 8.10(2H, d),             8.35(1H, dd), 8.65(1H, m);     IR(KBr) 1760, 1715, 1540, 1355, 1240;     ν.sub.max /cm.sup.-1     MS(m/z) 603 M.sup.+ !, 326, 166;     OR       α!.sub.D.sup.23° -5.4°(c=0.05,     ______________________________________             CHCl.sub.3).

4-Methoxycarbonyloxybenzoic acid (20)

Quantities: 4-hydroxybenzoic acid (19) (10.00 g, 0.07 mol), methyl chloroformate (11.34 g, 0.12 mol), sodium hydroxide (8.32 g, 0.208 mol), water (240 ml).

The experimental procedure was as described for the preparation of compound 4. The product was recrystallised from ethanol to yield white crystals.

Yield 12.00 g (82%); mp 177°-178° C.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)               3.95(3H, s), 7.30(2H, d), 8.15(2H, d), no obvious OH     δ   absorption;     IR(KBr)   3300-2300, 175.0, 1680, 1265, 940;     ν.sub.max /cm.sup.-1     MS(m/z)   196 M.sup.+ !, 152, 135, 59.     ______________________________________

Octyl 4-methoxycarbonyloxybenzoate (21)

Quantities: compound 20 (10.00 g, 0.049 mol), octan-1-ol (6.38 g, 0.049 mol), DEAD (8.53 g, 0.049 mol), triphenylphosphine (12.85 g, 0.049 mol).

The experimental procedure was as described for the preparation of compound 5. The crude product was purified by column chromatography (10% petrol/dichloromethane) to give a colourless oil which solidified on standing.

Yield 13.76 g (89%); mp 28°-30° C.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                0.90(3H, t), 1.20-1.50(10H, m), 1.70-1.85(2H, m),     δ    3.95(3H, s), 4.30(2H, t), 7.25(2H, d), 8.10(2H, d);     IR(KBr)    1765, 1720, 1250;     ν.sub.max /cm.sup.-1     MS(m/z)    308 M.sup.+ !, 196, 179, 152, 135.     ______________________________________

Decyl 4-methoxycarbonyloxybenzoate (22)

Quantities: compound 20 (10.00 g, 0.051 mol), decan-1-ol (8.08 g, 0.051 mol), DEAD (8.89 g, 0.051 mol), triphenylphosphine (13.38 g, 0.051 mol), THF (100 ml).

The experimental procedure was as described for the preparation of compound 5. The crude product was purified by column chromatography (20% petrol/dichloromethane) to give a colourless oil.

Yield 16.53 g (96%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                0.85(3H, t), 1.15-1.55(14H, m), 1.75(2H, m),     δ    3.90(3H, s), 4.30(2H, t), 7.25(2H, d), 8.10(2H, d);     IR(neat)   1770, 1720, 1260, 1220;     ν.sub.max /cm.sup.-1     MS(m/z)    336 M.sup.+ !, 197, 179, 152, 135.     ______________________________________

Octyl 4-hydroxybenzoate (23)

Quantities: compound 21 (13.76 g, 0.045 mol), ethanol (150 ml), aqueous ammonia (35% w/v, 150 ml).

The experimental procedure was as described for the preparation of compound 6.

Yield 9.56 g (85%); mp 46°-49° C.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)               0.90(3H, t), 1.20-1.55(10H, m), 1.75-1.90(2H, m),     δ   4.05(2H, t), 6.95(2H, d), 8.05(2H, d), no obvious OH               absorption;     IR(KBr)   3600-3100, 1670;     ν.sub.max /cm.sup.-1     MS(m/z)   250 M.sup.+ !, 138, 121.     ______________________________________

Decyl 4-hydroxybenzoate (24)

Quantities: compound 22 (16.53 g, 0.049 mol), ethanol (200 ml), aqueous ammonia (35% w/v, 100 ml).

The experimental procedure was as described for the preparation of compound 6. After removing the solvent in vacuo the crude product was purified by column chromatography (4% ethanol/dichloromethane) to yield a colourless solid.

Yield 12.07 g (88%); mp 44°-45° C.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                  0.90(3H, t), 1.20-1.60(14H, m), 4.05(2H, t),     δ      7.00(2H, d), 8.45(2H, d), 8.95(1H, s);     IR(KBr)      3600-3100, 1675, 1280;     ν.sub.max cm.sup.-1     MS(m/z)      278 M.sup.+ !, 138, 121, 93, 65, 55.     ______________________________________

(S)-(+)-4'-(2-Methylbutyloxy)-4-biphenylcarboxylic acid (26)

Quantities: (S)-4-cyano-4-(2-methylbutyloxy)cyanobiphenyl (25) (5.00 g, 0.02 mol), concentrated sulphuric acid (10 ml), water (10 ml), glacial acetic acid (100 ml).

The experimental procedure was as described for the preparation of compound 2 to give a white solid which was heated under reflux with a further, fresh acid mixture. The final white solid was recrystallised from glacial acetic acid to yield a white, crystalline solid.

Yield 3.00 g (83%); mesomorphic behaviour (°C.) K 240N 252.2 I (lit. K 239N 249 I).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3 +                0.95(3H, t), 1.05(3H, d), 1.30(1H, m), 1.60(1H, m),     DMSO)δ                1.90(1H, m), 4.85(2H, m), 7.00(2H, d), 7.55(2H, d),                7.65(2H, d), 8.10(2H, d), no obvious OH                absorption;     IR(KBr)ν.sub.max /cm.sup.-1                3300-2300, 1680, 1250, 950;     MS(m/z)    284 M.sup.+ !, 214, 197, 94;     OR          α!.sub.D.sup.22° +15.0°(c=0.02,     ______________________________________                DMF).

(S)-(+)-4-(2-Methylbutyloxy)-3-nitro-4'-biphenylcarboxylic acid (27)

Quantities: compound 26 (3.00 g, 0.01 mol), concentrated sulphuric acid (18 ml), concentrated nitric acid (9 ml), glacial acetic acid (40 ml).

The experimental procedure was as described for the preparation of compound 12 to give a pale yellow solid which was recrystallised from ethanol.

Yield 3.00 g (83 %); mesomorphic behaviour (°C.) K 145.2 S_(X) 150.2 S_(C) * 174

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)               1.00(3H, t), 1.10(3H, d), 1.35(1H, m), 1.60(1H, m),     δ   1.95(1H, m), 4.00(2H, m), 7.20(1H, d), 7.65(2H, d),               7.80(1H, dd), 8.10(1H, d), 8.20(2H, d), no obvious               OH absorption;     IR(KBr)   3700-3300, 3300-2300, 1690, 1540, 1350, 1260, 960;     ν.sub.max /cm.sup.-1     MS(m/z)   329 M.sup.+ !, 284, 259, 214, 71;     OR         α!.sub.D.sup.22° +6.8°(c=0.03,     ______________________________________               CHCl.sub.3).

(S)-(+)-Octyl 4- 4-(2-methylbutyloxy)-3-nitro-4'-biphenylcarbonyloxy!benzoate (28)

Quantities: compound 27 (1.50 g, 4.56 mmol), compound 23 (1.14 g, 4.56 mmol), DCC (1.13 g, 5.47 mmol), DMAP (0.06 g, 0.51 mmol), dichloromethane (50 ml).

The experimental procedure was as described for the preparation of compound 17. The product was purified by column chromatography (10% petrol/dichloromethane) and recrystallised from acetonitrile to give pale yellow crystals.

Yield 0.80 g (31%); mesomorphic behaviour (°C.) K 67.0 (S_(C) * 62.0) S_(A) * 132.9 I.

    ______________________________________     .sup.1 H NMR             0.90(3H, t), 0.95(3H, t), 1.10(3H, d), 1.20-1.55(11H, m),     (CDCl.sub.3)δ             1.60(1H, m), 1.80(2H, m), 2.00(1H, m), 4.00(2H, m),             4.35(2H, t), 7.20(1H, d), 7.35(2H, d), 7.70(2H, d),             7.80(1H, dd), 8.15(1H, d), 8.15(2H, d), 8.30(2H, d);     IR(KBr) 1740, 1705, 1535, 1355, 1265, 1070;     ν.sub.max cm.sup.-1     MS(m/z) 561 M.sup.+ !, 326, 166;     OR       α!.sub.D.sup.23° +3.8°(c=0.03,     ______________________________________             CHCl.sub.3).

4-Methoxycarbonyloxy-3-nitrobenzoic acid (30)

Quantities: 4-hydroxy-3-nitrobenzoic acid (29) (25.00 g, 0.137 mol), methyl chloroformate (21.20 g, 0.224 mol), sodium hydroxide (15.90 g, 0.397 mol), water (425 ml).

The experimental procedure was as described for the preparation of compound 4. The product was recrystallised from ethanol to give pale yellow crystals.

Yield 28.42 g (86%); mp 152°-154° C.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                4.00(3H, s), 7.45(1H, d), 8.35(1H, dd), 8.80(1H, d),     δ    no obvious OH absorption;     IR(KBr)    3300-2300, 1780, 1700, 1540, 1350, 1245, 940;     ν.sub.max /cm.sup.-1     MS(m/z)    241 M.sup.+ !, 166, 150, 136, 119, 90, 73.     ______________________________________

Octyl 4'- 4-(methoxycarbonyloxy)-3-nitrobenzoyloxy!-4-biphenylcarboxylate (31)

Quantities: compound 30 (2.41 g, 0.01 mol), compound 6 (3.26 g, 0.01 mol), DEAD (1.74 g, 0.01 mol), triphenylphosphine (2.62 g, 0.01 mol).

The experimental procedure was as described for the preparation of compound 9. The product was purified by column chromatography (10% petrol/dichloromethane) and finally recrystallised from ethanol to give a pale yellow solid.

Yield 1.75 g; mp 125°-126° C.

    ______________________________________     .sup.1 H NMR             0.90(3H, t), 1.20-1.55(10H, m), 1.80(2H, m), 4.00(3H, s),     (CDCl.sub.3)δ             4.35(2H, t), 7.35(1H, d), 7.50(2H, d), 7.70(2H, d),             7.70(2H, d), 8.00(2H, d), 8.50(1H, dd), 9.00(1H, d);     IR(KBr) 1735, 1720, 1705, 1540, 1345, 1260;     ν.sub.max /cm.sup.-1     MS(m/z) 549 M.sup.+ !, 491, 327, 214, 166, 120.     ______________________________________

(R)-(-)-Octyl 4'- 4-(1-ethylheptyloxy)-3-nitrobenzoyloxy!-4-biphenylcarboxylate (32)

Quantities: compound 31 (1.20 g, 2.44 mmol), (S)-(+)-nonan-3-ol (0.35 g, 2.44 mmol), DEAD (0.43 g, 2.44 mmol), triphenylphosphine (0.64 g, 2.44 mmol).

The experimental procedure was as described for the preparation of compound 5. The product was purified by column chromatography (10% petrol/dichloromethane) and recrystallised from ethanol to give pale yellow crystals.

Yield 0.50 g (33%); mp 39°-40° C.

    ______________________________________     .sup.1 H NMR             0.90(6H, 2t), 1.00(3H, t), 1.15-1.60(18H, m), 1.80(6H, m),     (CDCl.sub.3)δ             4.35(2H, t), 4.50(1H, m), 7.15(1H, d), 7.30(2H, d),             7.65(2H, d), 7.70(2H, d), 8.10(2H, d), 8.30(1H, dd),             8.65(1H, d);     IR(KBr) 1720, 1705, 1530, 1355, 1240;     ν.sub.max /cm.sup.-1     MS(m/z) 617 M+!, 326, 292, 214, 166;     OR       α!.sub.D.sup.21° -1.26°(c=0.02,     ______________________________________             CHCl.sub.3).

(R)-(-)-Octyl 4'- 4-(1-methylheptyloxy)benzoyloxy!-4-biphenylcarboxylate (33)

Quantities: compound 15 (1.40 g, 5.60 mmol), compound 6 (1.83 g, 5.60 mmol), DCC (1.39 g, 6.72 mmol), DMAP (0.08 g, 0.62 mmol).

The experimental procedure was as described for the preparation of compound 17. The compound was purified by column chromatography (i) 10% petrol/dichloromethane, (ii) 50% petrol/dichloromethane, (iii) dichloromethane! and recrystallised from ethanol to give colourless crystals.

Yield 3.01 g (96%); mesomorphic behaviour (°C.) K 57.4 S_(C) * 64.4N* 69.7 I.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                0.90(6H, 2t), 1.20-1.65(20H, m), 1.35(3H, d),     δ    1.80(2H, m), 4.35(2H, t), 4.50(1H, m), 6.95(2H, d),                7.30(2H, d), 7.65(4H, 2d), 8.10(2H, d), 8.15(2H, d);     IR(KBr)    1720, 1255;     ν.sub.max /cm.sup.-1     MS(m/z)    558 M.sup.+ !, 430, 325, 233, 121;     OR          α!.sub.D.sup.19° -4.5°(c=0.005,                CHCl.sub.3).     ______________________________________

(R)-(-)-1-Bromo-3-fluoro-4-(1-methylheptyloxy)benzene (35)

Quantities: 4-bromo-3-fluorophenol (34) (7.33 g, 0.038 mol), (S)-(+)-octan-2-ol (5.00 g, 0.038 mol), DEAD (6.69 g, 0.038 mol), triphenylphosphine (10.07 g, 0.038 mol).

The experimental procedure was as described for the preparation of compound 5. The product was purified by column chromatography (70% petrol/dichloromethane) to give a colourless oil.

Yield 10.62 g (92%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                  0.85(3H, t), 1.20-1.85(13H, m), 4.30(lH, m),     δ      6.85(1H, t), 7.15(1H, ddd), 7.20(1H, dd);     IR(neat)     1265;     ν.sub.max /cm.sup.-1     MS(m/z)      304 M.sup.+ !, 302 M.sup.+ !, 192, 190;     OR            α!.sub.D.sup.26° -1.7°(c=0.04,                  CHCl.sub.3).     ______________________________________

(R)-(-)-3-Fluoro-4-(1-methylheptyloxy)benzoic acid (36)

A solution of n-butyllithium (2.5M, 17.2 ml, 0.043 mol) in hexanes was added, dropwise, to a cooled (-78° C.), stirred solution of compound 35 (10.00 g, 0.033 mol) in dry THF (100 ml) under a dry nitrogen atmosphere and left to stir for 20 min. The resultant solution was poured into a slush of solid carbon dioxide and dry THF. This was left overnight at room temperature and then acidified with dilute hydrochloric acid. The TBF/water azeotrope was evaporated off in vacuo and the residue was dissolved in diethyl ether, washed with water and then extracted with 5% sodium hydroxide solution which was acidified with dilute hydrochloric acid. The product was extracted with diethyl ether and the ethereal solution was washed with water until acid-free, dried (MgSO₄) and evaporated in vacuo to leave an off-white, semi-solid.

Yield 4.15 g (47%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                0.85(3H, t), 1.35(3H, d), 1.15-1.90(10H, m),     δ    4.50(1H, m), 7.00(1H, t), 7.80(1H, d), 7.85(1H, d),                10.5-11.5(1H, s);     IR(KBr)    3500-2400, 1690, 1280;     ν.sub.max /cm.sup.-1     MS(m/z)    268 M.sup.+ !, 156, 139, 112, 83;     OR          α!.sub.D.sup.18° -7.0°(c=0.04,                CHCl.sub.3).     ______________________________________

(R)-(-)-Octyl 4'- 4-(1-methylheptyloxy)-3-fluorobenzoyloxy!-4-biphenylcarboxylate (37)

Quantities: compound 36 (2.00 g, 7.46 mmol), compound 6 (2.43 g, 7.46 mmol), DCC (1.85 g, 8.96 mmol), DMAP (0.10 g, 0.82 mmol).

The experimental procedure was as described for the preparation of compound 17. The crude product was purified by column chromatography (10% petrol/dichloromethane) and recrystallised from ethanol to give a white, crystalline solid.

Yield 1.50 g (35%), mesomorphic behaviour (°C.) K 61.2 S_(C) * 71.7 I.

    ______________________________________     .sup.1 H NMR             0.90(6H, 2t), 1.40(3H, d), 1.20-1.95(22H, m), 4.35(2H, t),     (CDCl.sub.3)δ             4.55(1H, m), 7.05(1H, t), 7.30(2H, d), 7.05(1H, t),             7.65(4H, 2d), 7.90(1H, d), 8.00(1H, m), 8.10(2H, d).     IR(KBr) 1725, 1705, 1280.     ν.sub.max /cm.sup.-1     MS(m/z) 504 M.sup.+ !, 251, 139.     OR       α!.sub.D.sup.26° -2.3°(c=0.01,     ______________________________________             CHCl.sub.3).

(S)-(+)-2-(2-Methylbutyloxy)benzonitrile (39)

Quantities: 2-hydroxybenzonitrile (38) (5.00 g, 0.042 mol), (S)-(-)-2-methylbutan-1-ol (3.70 g, 0.042 mol), DEAD (7.31 g, 0.042 mol), triphenylphosphine (11.01 g, 0.042 mol), THF (100 ml).

The experimental procedure was as described for the preparation of compound 5. The crude product was first washed with a 5% sodium hydroxide solution and then purified by column chromatography (10% petrol/dichloromethane) to yield a fawn coloured oil.

Yield 4.88 g (61%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)               0.95(3H, t), 1.05(3H, d), 1.35(1H, m), 1.60(1H, m),     δ   1.95(1H, m), 3.90(2H, m), 7.00(1H, t), 7.00(1H, dd),               7.50(1H, t), 7.50(1H, dd);     IR(neat)  2215, 1260;     ν.sub.max /cm.sup.-1     MS(m/z)   189 M.sup.+ !, 119;     OR         α!.sub.D.sup.26° +8.5°(c=0.03,     ______________________________________               CDCl.sub.3).

(R)-(-)-2-(1-Methylheptyloxy)benzonitrile (40)

Quantities: 2-hydroxybenzonitrile (38) (9.17 g, 0.077 mol), (S)-(+)-octan-2-ol (10.00 g, 0.077 mol), DEAD (13.41 g, 0.077 mol), triphenylphosphine (20.20 g, 0.077 mol).

The experimental procedure was as described for the preparation of compound 5. The crude product was purified by column chromatography (20% petrol/dichloromethane) to give a colourless oil.

Yield 17.70 g (100%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                0.90(3H, t), 1.35(3H, d), 1.15-1.90(10H, m),     δ    4.50(1H, m), 6.90-7.00(2H, m), 7.45-7.55(2H, d);     IR(neat)   2215, 1260;     ν.sub.max /cm.sup.-1     MS(m/z)    231 M.sup.+ !, 119, 111, 84, 69;     OR          α!.sub.D.sup.23° -55.6°(c=0.14,                CHCl.sub.3).     ______________________________________

(S)-(+)-5-Bromo-2-(2-methylbutyloxy)benzonitrile (41)

A mixture of compound 39 (4.25 g, 0.022 mol), bromine (12.31 g, 0.077 mol) and chloroform (50 ml) was heated under reflux overnight. A further portion of bromine (12.31 g, 0.077 mol) was then added and heating continued for another 24 h. The resultant solution was washed with a saturated solution of sodium thiosulphate and finally with water. The dichloromethane solution was dried (MgSO₄) and evaporated in vacuo and the crude oil was purified by column chromatography (10% petrol/dichloromethane) to yield a fawn oil.

Yield 5.56 g (94%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)                   0.95(3H, t), 1.05(3H, d), 1.35(1H, m),     δ       1.60(1H, m), 1.95(1H, m), 3.85(2H, m),                   6.85(1H, d), 7.60(1H, dd), 7.65(1H, d);     IR(neat)      2215, 1260;     ν.sub.max /cm.sup.-1     MS(m/z)       269 M.sup.+ !, 267 M.sup.+ !, 199, 197, 70, 54;     OR             α!.sub.D.sup.21.5° +7.1(c=0.04,     ______________________________________                   CHCl.sub.3).

(R)-(-)-5-Bromo-2-(1-methylheptyloxy)benzonitrile (42)

Quantities: compound 40 (12.34 g, 0.054 mol), bromine (17.15 g, 0.107 mol), chloroform (100 ml).

The experimental procedure was as described for the preparation of compound 41. The crude product was purified by column chromatography (20% petrol/dichloromethane) to give a fawn oil.

Yield 15.50 g (93%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)               0.85(3H, t), 1.45(3H, d), 1.15-1.55(8H, m),     δ   1.60(1H, m), 1.80(1H, m), 4.45(1H, m), 6.85(1H, d),               7.60(1H, dd), 7.65(1H, d);     IR(neat)  2220, 1255;     ν.sub.max /cm.sup.-1     MS(m/z)   311 M.sup.+ !, 309 M.sup.+ !, 199, 197, 112, 83, 70, 57;     OR         α!.sub.D.sup.28° -28.3°(c=0.03,               CHCl.sub.3).     ______________________________________

(S)-(+)-3-Cyano-4-(2-methylbutyloxy)benzoic acid (43)

Quantities: compound 41 (5.00 g, 0.016 mol), n-butyllithium (2.5M, 7.2 ml, 0.018 mol), THF (100 ml).

The experimental procedure was as described for compound 36 except that the n-butyllithium was added between -90° C. and -100° C. Acidification of the resultant benzoic acid lithium salt was achieved by boiling with glacial acetic acid. The benzoic acid was crashed out of solution by diluting with a large volume of water, the resultant product was washed with water (until acid-free) and then purified as described for compound 36 to leave an off-white semi-solid.

Yield 4.04 g (91%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3)               0.95(3H, t), 1.10(3H, d), 1.35(1H, m), 1.60(1H, m),     δ   2.00(1H, m), 4.00(2H, m), 7.05(1H, d), 8.25(1H, dd),               8.30(1H, d), no obvious OH absorption;     IR(KBr)   3400-2400, 2220, 1710, 1260, 920;     ν.sub.max /cm.sup.-1     MS(m/z)   233 M.sup.+ !, 163, 119, 71;     OR         α!.sub.D.sup.28.5° +9.9°(c=0.04,               CHCl.sub.3).     ______________________________________

(R)-(-)-3-Cyano-4-(1-methylheptyloxy)benzoic acid (44)

Quantities: compound 42 (5.00 g, 0.016 mol), n-butyllithium (2.5M, 7.2 ml, 0.018 mol), THF (100 ml).

The experimental procedure was as described for the preparation of compound 36 to give a fawn solid.

Yield 3.23 g (73%); mp 78°-80° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.35(3H, d), 1.15-1.95(10H, m),                4.60(1H, m), 7.00(1H, d), 8.25(1H, dd), 8.30(1H,                d), no obvious OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                3400-2500, 2215, 1695, 1260;     MS (m/z)   275 M.sup.+ !, 163, 146, 112, 83, 71;     OR          α!.sub.D.sup.22° -9.7°(c=0.04,                CHC1.sub.3).     ______________________________________

(S)-(+)-Octyl 4'- 3-cyano-4-(2-methylbutyloxy)benzoyloxy!-4-biphenylcarboxylate (45)

Quantities: compound 43 (1.42 g, 6.13 mmol), compound 6 (2.00 g, 6.13 mmol), DCC (1.52 g, 7.36 mmol), DMAP (0.08 g, 0.67 mmol).

The experimental procedure was as described for the preparation of compound 17. The product was purified by column chromatography (20% petrol/dichloromethane) and recrystallised from ethanol to give white crystals.

Yield 1.00 g (30%); mesomorphic behaviour (°C.) K 126.5 S_(A) * 133.3 I.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3) δ                0.90(3H, t), 0.95(3H, t), 1.10(3H, d), 1.20-                2.10(15H, m), 4.00(2H, m), 4.35(2H, t),                7.10(1H, d), 7.30(2H, d), 7.65(2H, d), 7.70(2H, d),                8.10(2H, d), 8.35(1H, dd), 8.45(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                2220, 1735, 1725, 1245;     MS (m/z)   541 M.sup.+ !, 286, 216, 146, 71;     OR          α!.sub.D.sup.25° +3.9°(c=0.01,     ______________________________________                acetone).

(R)-(-)-Octyl 4'- 3-cyano-4-(1-methylheptyloxy)benzoyloxy!-4-biphenylcarboxylate (46)

Quantities: compound 44 (1.50 g, 5.45 mmol), compound 6 (1.78 g, 5.45 mmol), DCC (1.35 g, 6.54 mmol), DMAP (0.07 g, 0.57 mmol).

The experimental procedure was as described for the preparation of compound 17. Purification was by column chromatography with the following solvent systems: (i) 30% petrol/dichloromethane, (ii) 20% diethyl ether/petrol, (iii) 30% diethyl ether/petrol. Attempted recrystallisation with the following solvents, ethanol, ethanol and ethyl acetate, methanol and acetonitrile, in each case gave a jelly-like mass. The removal of all solvents in vacuo left a colourless, sticky solid.

Yield 1.41 g (44%); mesomorphic behaviour (°C.) K ? S_(C) * 52.1 S_(A) * 64.5 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.45(3H, d), 1.20-1.95(22H, m),                4.35(2H, t), 4.65(1H, m), 7.05(1H, d), 7.30(2H,                d), 7.65(2H, d), 7.70(2H, d), 8.10(2H, d), 8.35(1H,                dd), 8.45(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                2215, 1730, 1710, 1245;     MS (m/z)   583 M.sup.+ !, 258, 146;     OR          α!.sub.D.sup.20° -14.6°(c=0.03,                CHCl.sub.3).     ______________________________________

(S)-(+)-3-Cyano-4-(2-methylbutyloxy)phenylboronic acid (47)

Quantities: compound 41 (3.00 g, 0.012 mol), n-butyllithium (2.5M, 5.28 ml, 0.013 mol), trimethyl borate (2.70 g, 0.024 mol).

The experimental procedure for the preparation of the lithium salt was as described in the preparation of compound 43. A solution of trimethyl borate (2.70 g, 0.024 mol) in dry THF (10 ml) was added dropwise to the lithium salt solution. The resultant mixture was allowed to warm to room temperature overnight whilst stirring and dilute hydrochloric acid was then added. The THF/water azeotrope was removed in vacuo and the remaining residue was dissolved in diethyl ether and washed with water until acid-free. The ether was dried (MgSO₄) and removed in vacuo to leave a fawn solid.

Yield 2.54 g (95%); mp 186°-188° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.95(3H, t), 1.10(3H, d), 1.40(1H, m), 1.65(1H, m),                2.00(1H, m), 4.00(2H, m), 7.10(1H, d), 8.30(1H,                dd), 8.35(1H, d), no obvious OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                3700-3100, 2215, 1265;     MS (m/z)   305 M.sup.+ !, 135;     OR          α!.sub.D.sup.21° +6.2°(c=0.006,                CHCl.sub.3).     ______________________________________

(R)-(-)-3-Cyano-4-(1-methylheptyloxy)phenylboronic acid (48)

Quantities: compound 42 (5.00 g, 0.016 mol), n-butyllithium (2.5M, 7.2 ml, 0.018 mol), trimethyl borate (3.33 g, 0.032 mol), TBF (100 ml).

The procedure was as described for the preparation of compounds 47.

Yield 3.90 g (87%); mp 67°-70° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                   0.90(3H, t), 1.35(3H, d), 1.15-1.95(10H, m),                   4.60(1H, m), 7.05(1H, d), 8.30(1H, dd),                   8.35(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                   3700-3100, 2215, 1260;     MS (m/z)      275 M.sup.+ !, 236, 119, 69;     OR             α!.sub.D.sup.25° -47.1°(c=0.01,                   CHCl.sub.3).     ______________________________________

(S)-(+)-5-Hydroxy-2-(2-methylbutyloxy)benzonitrile (49)

A mixture of compound 47 (3.00 g, 0.014 mol), hydrogen peroxide (30% w/v, 150 ml) and THF (200 ml) was heated under reflux for 3 h. The water/THF mixture was removed in vacuo and the oily residue was dissolved in diethyl ether and washed with water. The ether was dried (MgSO₄) and evaporated in vacuo to give a viscous, fawn oil.

Yield 2.01 g (70%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.05(3H, d), 1.35(1H, m), 1.60(1H, m),                1.90(1H, m), 3.80(2H, m), 6.25-6.50(1H, s),                6.85(1H, dd), 7.05(1H, d), no obvious                OH absorption;     IR (neat) ν.sub.max /cm.sup.-1                3700-3100, 2220, 1230;     MS (m/z)   205 M.sup.+ !, 135;     OR          α!.sub.D.sup.22° +8.5(c=0.02, CHCl.sub.3).     ______________________________________

(R)-(-)-5-Hydroxy-2-(1-methylheptyloxy)benzonitrile (50)

Quantities: compound 48 (5.32 g, 0.019 mol), hydrogen peroxide (30% w/v, 50 ml), THF (100 ml).

The experimental procedure was as described for the preparation of compound 49 to yield a viscous, fawn oil which solidified on standing.

Yield 2.92 g (62%); mp 34°-36° C.

    ______________________________________     .sup.1 H NMR(CDCl.sub.3) δ                0.85(3H, t), 1.30(3H, d), 1.20-1.85(10H, m),                4.35(1H, m), 6.85(1H, d), 7.05(1H, dd), 7.05(1H,                d), no obvious OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                3700-3000, 2215, 1230;     MS (m/z)   247 M.sup.+ !, 135, 55;     OR          α!.sub.D.sup.21° -46.0°(c=0.04,                CHCl.sub.3).     ______________________________________

(R)-(-)-2-(1-Methylheptyloxy)benzotrifluoride (52)

Quantities: 2-hydroxybenzotrifluoride (51) (5.00 g, 0.031 mol), (S)-(+)-octan-2-ol (4.00 g, 0.031 mol), DEAD (5.37 g, 0.031 mol), triphenylphosphine (8.09 g, 0.031 mol).

The experimental procedure was as described for the preparation of compound 5. The product was purified by column chromatography (50% petrol/dichloromethane) to yield a colourless oil.

Yield 5.00 g (59%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                 0.90(3H, t), 1.15-1.85(13H, m), 4.45(1H, m),                 6.95(2H, 2m), 7.45(1H, m), 7.55(1H, m);     IR (neat) ν.sub.max /cm.sup.-1                 1255;     MS (m/z)    274 M.sup.+ !, 183, 162, 142, 112;     OR           α!.sub.D.sup.20° -23.3°(c=0.02,                 CHCl.sub.3).     ______________________________________

(R)-(-)-5-Bromo-2-(1-methylheptyloxy)benzotrifluoride (53)

Quantities: compound 52 (4.87 g, 0.018 mol), bromine (5.68 g, 0.036 mol), chloroform (100 ml).

The experimental procedure was as described for the preparation of compound 41 except only one portion of bromine was used. The product was purified by column chromatography (50% petrol/dichloromethane) to give a colourless oil.

Yield 6.02 g (95%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                   0.85(3H, t), 1.20-1.80(10H, m), 1.40(3H, d),                   4.40(1H, m), 6.85(1H, d), 7.35(1H, dd),                   7.60(1H, d);     IR (neat) ν.sub.max /cm.sup.-1                   1250;     MS (m/z)      304 M.sup.+ !, 302 M.sup.+ !, 192;     OR             α!.sub.D.sup.26° -12.0°(c=0.03,                   CHCl.sub.3).     ______________________________________

(R)-(-)-3-α,α,α-Trifluoromethyl-4-(1-methylheptyloxy)benzoic acid (54)

Quantities: compound 53 (4.00 g, 0.011 mol), n-butyllithium (2.5M, 5.44 ml, 0.014 mol), THF (100 ml).

The experimental procedure was as described for the preparation of compound 36 to give an off-white solid.

Yield 2.82 g (81%); mp 92°-95° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.40(3H, d), 1.20-1.95(10H, m),                4.60(1H, m), 7.00(1H, d), 8.25(1H, dd), 8.30(1H,                d), no obvious OH absorption;     IR ν.sub.max /cm.sup.-1                3300-2300, 1700, 1260, 940;     MS (m/z)   318 M.sup.+ !, 276, 164, 146, 121, 83, 71, 56;     OR          α!.sub.D.sup.21° -45.5°(c=0.03,                CHCl.sub.3).     ______________________________________

(R)-(-)-Octyl 4'- 4-(1-methylheptyloxy)-3-ααα-trifluoromethylbenzoyloxy!-4-biphenylcarboxylate (55)

Quantities: compound 54 (1.50 g, 4.72 mmol), compound 6 (1.54 g, 4.72 mmol), DCC (1.17 g, 5.66 mmol), DMAP (0.06 g, 0.52 mmol).

The experimental procedure was as described for the preparation of compound 17. The product was purified by column chromatography (i) dichloromethane, (ii) 1% ethanol/dichloromethane, (iii) 2% ethanol/dichloromethane! and recrystallised from ethanol to give a sticky, colourless solid.

Yield 1.34 g (50%); mesomorphic behaviour (°C.) K 60.5 (S_(C) * 58.7) S_(A) * 68.1 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.40(3H, d), 1.60-1.95(22H, m),                4.35(2H, t), 4.60(1H, m), 7.05(1H, d), 7.30(2H, d),                7.65(2H, d), 7.70(2H, d), 8.10(2H, d), 8.35(1H, dd),                8.45(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1730, 1710, 1240;     MS (m/z)   626 M.sup.+ !, 584, 454, 326, 146;     OR          α!.sub.D.sup.18° -22.4°(c=0.01,                CHCl.sub.3).     ______________________________________

4-Cyano-4'-decyloxybiphenyl (57)

A mixture of 4-cyano-4'-hydroxybiphenyl (56) (10.10 g, 0.052 mol), 1-bromodecane (14.38 g, 0.065 mol), anhydrous potassium carbonate (37.32 g, 0.27 mol), butanone (300 ml) and a trace of potassium iodide was heated under reflux overnight. The cooled solution was filtered to remove inorganic salts and the solvent was removed in vacuo. The residual oil was distilled (to remove excess bromide) and finally purified by column chromatography (dichloromethane) to yield a colourless, low melting solid.

Yield 17.00 g (98%); mesomorphic behaviour (°C.) K 42.3N 50.8 I (lit. K 44N 51.5 I).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.15-1.60(14H, m), 1.80(2H, m),                4.00(2H, t), 7.00(2H, d), 7.50(2H, d), 7.60(2H, d),                7.70(2H, d);     IR (KBr) ν.sub.max /cm.sup.-1                2215, 1255;     MS (m/z)   335 M.sup.+ !, 195, 69.     ______________________________________

4'-Decyloxy-4-biphenylcarboxylic acid (58)

Quantities: compound 57 (17.00 g, 0.051 mol), concentrated sulphuric acid (40 ml), water (40 ml), glacial acetic acid (200 ml).

The experimental procedure was as described for the preparation of compound 26 to yield a colourless, crystalline solid.

Yield 16.06 g (89%); mesomorphic behaviour (°C.) K 171 S_(C) N 253.5 I (lit. K 172.5 S_(C) 256.5N 257 I).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3  + DMSO) δ                    0.85(3H, t), 1.15-1.55(14H, m), 1.80(2H,                    m), 4.00(2H, t), 6.95(2H, d), 7.55(2H, d),                    7.60(2H, d), 8.05(2H, d), no obvious                    OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                    3300-2400, 1680, 1255;     MS (m/z)       354 M.sup.+ !, 214, 197, 69.     ______________________________________

(S)-(+)-3-Cyano-4-(2-methylbutyloxy)phenyl 4'-decyloxy-4-biphenylcarboxylate (59)

Quantities: compound 49 (1.42 g, 6.13 mmol), compound 58 (2.00 g, 6.13 mmol), DCC (1.52 g, 7.36 mmol), DMAP (0.08 g, 0.67 mmol).

The experimental procedure was as described for the preparation of compound 17. The product was purified by column chromatography (20% petrol/dichloromethane) and recrystallised from ethanol to give a white solid.

Yield 1.00 g (30%); mesomorphic behaviour (°C.) K 94.2 S_(C) * 112.7 S_(A) * 168.7 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.00(3H, t), 1.10(3H, d), 1.15-                2.05(19H, m), 3.90(2H, m), 4.00(2H, t), 7.00(1H,                d), 7.00(2H, d), 7.40(1H, dd), 7.45(1H, d), 7.60(2H,                d), 7.70(2H, d), 8.20(2H, d);     IR (KBr) ν.sub.max /cm.sup.-1                2215, 1730, 1265;     MS (m/z)   541 M.sup.+ !, 337, 197, 55;     OR          α!.sub.D.sup.25° +2.9°(c=0.01,                CHCl.sub.3).     ______________________________________

(R)-(-)-3-Cyano-4-(1-methylheptyloxy)phenyl 4'-decyloxy-4-biphenylcarboxylate (60)

Quantities: compound 50 (1.50 g, 6.07 mmol), compound 58 (2.15 g, 6.07 mmol), DCC (1.50 g, 7.29 mmol), DMAP (0.08 g, 0.67 mmol), dichloromethane/THF (100 ml).

The experimental procedure was as described for the preparation of compound 17. The product was purified by column chromatography (i) 30% petrol/dichloromethane, (ii) 40% petrol/dichloromethane! and recrystallised from ethanol to give a pure white solid.

Yield 0.90 g (25%); mesomorphic behaviour (°C.) K 64.9 S_(C) * 100.2 S_(A) * 118.8 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.20-1.95(32H, m), 4.05(2H, t),                4.50(1H, m), 7.00(1H, d), 7.00(2H, d), 7.40(1H,                dd), 7.45(1H, d), 7.60(2H, d), 7.70(2H, d), 8.20(2H,                d);     IR (KBr) ν.sub.max /cm.sup.-1                2220, 1730, 1280, 1255;     MS (m/z)   583 M.sup.+ !, 197, 57;     OR          α!.sub.D.sup.25° -16.7°(c=0.02,                CHCl.sub.3).     ______________________________________

(S)-(+)-1-(2-Methylbutyloxy)-2-nitrobenzene (62)

Quantities: 2-nitrophenol (61) (5.00 g, 0.036 mol), (S)-(-)-2-methylbutan-1-ol (3.17 g, 0.036 mol), DEAD (6.27 g, 0.036 mol), triphenylphosphine (9.44 g, 0.036 mol).

The experimental procedure was as described for the preparation of compound 5. The product was purified by column chromatography (10% petrol/dichloromethane) to give a pale yellow oil.

Yield 6.32 g (84%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.95(3H, t), 1.05(3H, d), 1.35(1H, m), 1.60(1H,                m), 1.95(1H, m), 3.90(2H, m), 7.00(1H, t),                7.05(1H, dd), 7.50(1H, t), 7.80(1H, dd);     IR (neat) ν.sub.max /cm.sup.-1                1520, 1350, 1255;     MS (m/z)   209 M.sup.+ !, 139, 70, 55, 43;     OR          α!.sub.D.sup.21.5° +2.7°(c=0.04,                CHCl.sub.3).     ______________________________________

(S)-(+)-1-Bromo-4-(2-methylbutyloxy)-3-nitrobenzene (63)

Method 1

Quantities: compound 62 (2.46 g, 0.012 mol), bromine (7.67 g, 0.048 mol), chloroform (100 ml).

The experimental procedure was as described for the preparation of compound 41. The product was purified by column chromatography (10% petrol/dichloromethane) to give a pale yellow oil.

Yield 1.75 g (51%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.00(3H, d), 1, 30(1H, m), 1.55(1H,                m), 1.90(1H, m), 3.90(2H, m), 6.95(1H, d),                7.60(1H, dd), 7.95(1H, d);     IR (neat) ν.sub.max /cm.sup.-1                1525, 1350, 1255;     MS (m/z)   289 M.sup.+ !, 287 M.sup.+ !, 219, 217, 70, 63, 55;     OR          α!.sub.D.sup.26° +4.7°(c=0.04,                CHCl.sub.3).     ______________________________________

Method 2

Quantities: 4-bromo-2-nitrophenol (64) (5.00 g, 0.023 mol), (S)-(-)-2-methylbutan-1-ol (2.03 g, 0.023 mol), DEAD (4.01 g, 0.023 mol), triphenylphosphine (6.03 g, 0.023 mol).

The experimental procedure was as described for the preparation of compound 5. The product was purified by column chromatography (10% petrol/dichloromethane) to give a pale yellow oil.

Yield 6.10 g (92%).

Spectra as for method 1.

(R)-(-)-1-(1-Methylheptyloxy)-2-nitrobenzene (65)

Quantities: 2-nitrophenol (61) (3.34 g, 0.024 mol), (S)-(+)-octan-2-ol (3.13 g, 0.024 mol), DEAD (4.01 g, 0.024 mol), triphenylphosphine (6.29 g, 0.024 mol).

The experimental procedure was as described for the preparation of compound 5. The product was purified by column chromatography (50% petrol/dichloromethane) to give a pale yellow oil.

Yield 4.59 g (76%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                 0.85(3H, t), 1.35(3H, d), 1.15-1.80(10H, m),                 4.50(1H, m), 6.90-7.00(2H, m), 7.70-7.80(2H,                 m);     IR (neat) νmax/cm.sup.-1                 1525, 1355, 1255;     MS (m/z)    251 M.sup.+ !, 139, 111, 84, 69;     OR           α!.sub.D.sup.23° -51.3°(c=0.04,                 CHCl.sub.3).     ______________________________________

(R)-(-)-1-Bromo-4-(1-methylheptyloxy)-3-nitrobenzene (66)

Method 1

Quantities: compound 65 (6.25 g, 0.025 mol), bromine (11.99 g, 0.075 mol), chloroform (100 ml).

The experimental procedure was as described for the preparation of compound 41. The crude product was purified by column chromatography (20% petrol/dichloromethane) to give a pale yellow oil.

Yield 5.22 g (63%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.40(3H, d), 1.20-1.55(8H, m),                1.60(1H, m), 1.75(1H, m), 4.45(1H, m), 6.95(1H,                d), 7.60(1H, dd), 7.90(1H, d);     IR (neat) ν.sub.max /cm.sup.-1                1525, 1350, 1280;     MS (m/z)   331 M.sup.+ !, 329 M.sup.+ !, 219, 217, 112, 83, 70;     OR          α!.sub.D.sup.22° -43.7°(c=0.03,                CHCl.sub.3).     ______________________________________

Method 2

Quantities: 4-bromo-2-nitrophenol (64) (3.00 g, 0.014 mol), (S)-(+)-octan-2-ol (1.79 g, 0.014 mol), DEAD (2.40 g, 0.014 mol), triphenylphosphine (3.61 g, 0.014 mol).

The experimental procedure was as described for the preparation of compound 41 and purification was carried out by column chromatography (30% petrol/dichloromethane).

Yield 2.67 g (58%).

Spectra as for method 1.

4-Bromo-4'-decyloxybiphenyl (68)

Quantities: 4-bromo-4'-hydroxybiphenyl (67) (20.00 g, 0.08 mol), 1-bromodecane (22.12 g, 0.10 mol), anhydrous potassium carbonate (57.10 g, 0.413 mol), potassium iodide (trace), butanone (500 ml).

The experimental procedure was as described for the preparation of compound 57. The cooled mixture of product and inorganic salts was filtered off and washed carefully with dilute hydrochloric acid to remove the potassium carbonate. The white product was then washed with water until acid-free and heated under reflux with a minimum volume of ethanol to remove traces of 1-bromodecane. The product was filtered off, washed with cold ethanol and dried in vacuo to yield colourless crystals.

Yield 29.00 g (93%); mp 117°-119° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.15-1.55(14H, m), 1.80(2H, m),                4.00(2H, t), 6.95(2H, d), 7.40(2H, d), 7.50(2H, d),                7.55(2H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1255;     MS (m/z)   390 M.sup.+ !, 388 M.sup.+ !, 250, 248, 162, 138, 99, 83,     ______________________________________                69.

4'-Decyloxybiphenyl-4-ylboronic acid (69)

Method 1

Quantities: compound 68 (8.00 g, 0.021 mol), n-butyllithium (2.5M, 9.2 ml, 0.023 mol), trimethyl borate (4.36 g, 0.042 mol), THF (800 ml).

The procedure was as described for the preparation of compound 43 but the addition of the butyllithium was started when the solution was at -60° C. and cooled further, to -70° C., during the addition such that the bromide (68) remained in solution. The blue-white solid was filtered off and washed with water until acid-free and dried in vacuo.

Yield mp

    ______________________________________     .sup.1 H NMR (CDCl.sub.3  + DMSO) δ                    0.35(3H, t), 0.65-1.05(10H, m), 1.30(2H,                    m), 2.25(2H, s), 3.45(2H, t), 6.90(2H, d),                    7.05(4H, 2d), 7.40(2H, d), no obvious                    OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                    3600-3100, 1255;     MS (m/z)       354 M.sup.+ !, 326, 310, 186, 170.     ______________________________________

Method 2

A stirred mixture of magnesium turnings (0.62 g, 0.026 mol), compound 68 (10.11 g, 0.026 mol) and dry THF (100 ml) was heated under reflux in an atmosphere of dry nitrogen. A few drops of 1,2-dibromoethane were added and the resultant mixture heated under reflux for 3 h. TLC analysis (dichloromethane) revealed a complete reaction. The Grignard reagent was cooled to 0° C. and trimethyl borate (5.34 g, 0.051 mol) in dry TBF (20 ml) was added and the resultant mixture left to stir overnight. The mixture was acidified with dilute hydrochloric acid and left for a further 1 h. The solvent was removed in vacuo and the remaining aqueous mixture was filtered off. The blue-white solid was washed with water until acid-free and dried (P₂ O₅) in vacuo.

Yield 8.77 g (95%).

Spectra as for method 1.

(R)-(-)-4"-Decyloxy-4-(1-methylheptyloxy)-3-cyanoterphenyl (70)

A vigorously stirred mixture of compound 42 (1.50 g, 4.84 mmol), compound 69 (2.05 g, 5.81 mmol), aqueous sodium carbonate (2M, 20 ml), tetrakis(triphenylphosphine palladium(0) (0.28 g, 0.24 mmol) and dimethoxyethane (100 ml) was heated under reflux, overnight, in a dry nitrogen atmosphere. The cooled mixture was washed with a large volume of water, dried (MgSO₄) and filtered over hyflo filter aid. The solvent was evaporated in vacuo and the residue was purified by column chromatography (70% petrol/dichloromethane) and recrystallised from ethanol to give white crystals.

Yield 1.20 g (46%); mesomorphic behaviour (°C.) K 65.3 (S_(C) * 60.0) S_(A) * 100.1 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.20-1.60(23H, m), 1.40(3H, d),                1.75-1.95(3H, m), 4.00(2H, t), 4.50(1H, m),                7.00(2H, d), 7.05(1H, d), 7.55(4H, 2d), 7.65(2H, d),                7.75(1H, dd), 7.80(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                2215, 1260, 1250;     MS (m/z)   539 M.sup.+ !, 447, 427, 287, 71;     OR          α!.sub.D.sup.27° -16.2°(c=0.03,                CHCl.sub.3).     ______________________________________

(S)-(+)-4"-Decyloxy-4-(2-methylbutyloxy)-3-nitroterphenyl (71)

Quantities: compound 63 (1.50 g, 5.21 mmol), compound 69 (2.21 g, 6.25 mmol), aqueous sodium carbonate (2M, 20 ml), tetrakis(triphenylphosphine)palladium(0) (0.30 g, 0.26 mmol), dimethoxyethane (100 ml).

The experimental procedure was as described for the preparation of compound 70. The product was purified by column chromatography (i) 50% petrol/dichloromethane; (ii) 80% petrol/dichloromethane)! and recrystallised from ethanol to yield a pale yellow solid.

Yield 1.14 g (42%); mesomorphic behaviour (°C.) K 71.8 S_(A) * 153.8 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.00(3H, t), 1.10(3H, d), 1.15-                2.05(19H, m), 3.95(2H, m), 4.00(2H, t), 7.00(2H,                d), 7.15(1H, d), 7.55(2H, d), 7.60(2H, d), 7.65(2H,                d), 7.75(1H, dd), 8.10(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1540, 1340, 1280, 1250;     MS (m/z)   517 M.sup.+ !, 447, 307, 261, 71, 55;     OR          α!.sub.D.sup.20° +2.4°(c=0.01,                CHCl.sub.3).     ______________________________________

(R)-(-)-4"-Decyloxy-4-(1-methylheptyloxy)-3-nitroterphenyl (72)

Quantities: compound 66 (1.50 g, 4.55 mmol), compound 69 (1.93 g, 5.46 mmol), sodium carbonate (2M, 20 ml), tetrakis(triphenylphosphine)palladium(0) (0.27 g, 0.23 mmol), dimethoxyethane (100 ml).

The experimental procedure was as described for the preparation of compound 70. The crude product was purified by column chromatography (70% petrol/dichloromethane) and recrystallised from ethanol to give a bright yellow solid.

Yield 0.78 g (31%); mesomorphic behaviour (°C.) K 46.7 S_(C) * 53.5 S_(A) * 96.0 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.40(3H, d), 1.20-1.90(26H, m),                4.00(2H, t), 4.55(1H, m), 7.00(2H, d), 7.15(1H,                d), 7.55(2H, d), 7.60(2H, d), 7.65(2H, d), 7.75(1H,                dd), 8.05(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1535, 1360, 1250;     MS (m/z)   559 M.sup.+ !, 447, 307, 121, 71;     OR          α!.sub.D.sup.21° -4.2°(c=0.03,                CHCl.sub.3).     ______________________________________

1-(4'-Decyloxybiphenyl-4-yl)-2-(1-hydroxy-1-methylethyl)ethyne (73)

A stirred mixture of compound 68 (15.00 g, 0.039 mol), 2-methylbut-3-yn-2-ol (7.15 g, 0.085 mol), copper(I) iodide (0.34 g, 1.80 mmol), tetrakis(triphenylphosphine)palladium(0) (2.89 g, 2.50 mmol) and diisopropylamine (150 ml) was heated under reflux in a dry nitrogen atmosphere for 24 h. The resultant mass was dissolved in THF and filtered over hyflo filter aid to remove inorganic materials. Volatile materials were removed in vacuo and the brown solid was recrystallised from ethanol to give a white, fluffy solid.

Yield 12.92 g (85%); mp 126°-127° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.20-1.60(14H, m), 1.60(6H, 2s),                1.80(2H, m), 2.00(1H, s), 4.00(2H, t), 6.95(2H, d),                7.45(2H, d), 7.50(4H, 2d);     IR (KBr) ν.sub.max /cm.sup.-1                3700-3100, 1255;     MS (m/z)   392 M.sup.+ !, 377, 252, 237.     ______________________________________

4'-Decyloxybiphenyl-4-ylethyne (74)

Compound 73 (12.90 g, 0.033 mol) and sodium hydroxide () was boiled for 1 h in toluene (100 ml) under a dry nitrogen atmosphere and the resultant toluene/acetone mixture removed in a Dean-Stark apparatus. As the toluene mixture was removed fresh toluene was added to the reaction mixture. TLC analysis (dichloromethane) revealed a complete reaction. The sodium hydroxide was filtered off and the toluene washed with water, dried (MgSO₄) and removed in vacuo to leave a metallic-beige solid.

Yield 10.74 g (97%); mp 82°-84° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.20-1.55(14H, m), 1.80(2H, m),                3.10(1H, s), 4.00(2H, t), 6.95(2H, d), 7.50(6H, 3d);     IR (KBr) ν.sub.max /cm.sup.-1                3290, 1255;     MS (m/z)   334 M.sup.+ !, 194, 165.     ______________________________________

(S)-(+)-1- 3-Cyano-4-(2-methylbutyloxy)phenyl!-2-(4'-decyloxybiphenyl-4-yl)ethyne (75)

Quantities: compound 41 (2.00 g, 7.46 mmol), compound 74 (2.99 g, 8.95 mmol), copper(I) iodide (0.29 g, 1.53 mmol), terakis(triphenylphosphine)palladium(0) (0.43 g, 0.37 mmol), triethylamine (100 ml).

The experimental procedure was as described for the preparation of compound 73. The crude product was purified by column chromatography, (i) 20% petrol/dichloromethane, (ii) 40% petrol/dichloromethane! and recrystallised from ethanol to give a white solid.

Yield 0.80 g (21%); mesomorphic behaviour (°C) K 63.5 S_(C) * 104.1 S_(A) * 152.6 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.00(3H, t), 1.10(3H, d), 1.20-                1.70(16H, m), 1.75-2.05(3H, m), 3.90(2H, m),                4.00(2H, t), 6.95(1H, d), 7.00(2H, d), 7.55(6H, 3d),                7.65(1H, dd), 7.75(1H, d), ;     IR (KBr) ν.sub.max /cm.sup.-1                2215, 1255;     MS (m/z)   521 M.sup.+ !, 451, 427, 311, 57, 43;     OR          α!.sub.D.sup.24° +12.8°(c=0.01,                CHCl.sub.3).     ______________________________________

(R)-(-)-1- 3-Cyano-4-(1-methylheptyloxy)phenyl!-2-(4'-decyloxybiphenyl-4-yl)ethyne (76)

Quantities: compound 42 (2.00 g, 6.45 mmol), compound 74 (2.59 g, 7.74 mmol), copper (I) iodide (0.12 g, 0.65 mmol), tetrakis(triphenylphosphine)palladium(0) (1.49 g, 1.29 mmol), triphenylphosphine (60 ml).

The experimental procedure was as described for the preparation of compound 73. The crude product was purified by column chromatography (50% petrol/dichloromethane) and recrystallised from ethanol to give a pale-yellow solid.

Yield 1.44 g (40%); mesomorphic behaviour (°C.) K 60.3 S_(A) * 105.6 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.35(3H, d), 1.20-1.55(26H, m),                1.55(1H, m), 1.80(2H, m), 4.00(2H, t), 4.50(1H,                m), 6.95(1H, d), 7.00(2H, d), 7.55(6H, 3d),                7.65(1H, dd), 7.75(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                2260, 1270;     MS (m/z)   563 M.sup.+ !, 451, 427, 311, 71;     OR          α!.sub.D.sup.28° -11.4°(c=0.02,                CHCl.sub.3).     ______________________________________

(S)-(+)-1- 4-(2-Methylbutyloxy)-3-nitrophenyl!-2-(4'-decyloxybiphenyl-4-yl)ethyne (77)

Quantities: compound 63 (2 g, 6.94 mmol), compound 74 (2.78 g, 8.32 mmol), copper(I) iodide (0.26 g, 1.37 mmol), tetrakis(triphenylphosphine)palladium(0) (0.40 g, 0.35 mmol), triethylamine (100 ml).

The experimental procedure was as described for the preparation of compound 73. The crude material was purified by column chromatography (i) 70% petrol/dichloromethane, (ii) 50% petrol/dichloromethane! and recrystallised from ethanol and ethyl acetate to give a yellow, crystalline solid.

Yield 0.75 g (20%); mesomorphic behaviour (°C.) K 60.0 S_(C) * 90.1 S_(A) * 144.2 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.85(3H, t), 0.95(3H, t), 1.05(3H, d), 1.20-                1.70(16H, m), 1.80(2H, m), 1.95(1H, m), 3.95(2H,                m), 4.00(2H, t),     6.95(2H,   d), 7.05(1H, d), 7.55(6H, 3d), 7.65(1H, dd),                8.00(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1535, 1350, 1265;     MS (m/z)   541 M.sup.+ !, 471, 331, 71, 55;     OR          α!.sub.D.sup.28° +4.2(c=0.02, CHCl.sub.3).     ______________________________________

(R)-(-)-1- 4-(1-Methylheptyloxy)-3-nitrophenyl!-2-(4'-decyloxybiphenyl-4-yl)ethyne (78)

Quantities: compound 66 (2.00 g, 6.06 mmol), compound 74 (2.43 g, 7.27 mmol), tetrakis(triphenylphosphine)palladium(0) (0.35 g, 0.30 mmol), copper(I) iodide (0.23 g, 1.21 mmol), triethylamine (100 ml).

The experimental procedure was as described for the preparation of compound 73. The crude product was purified by column chromatography (i) 80% petrol/dichloromethane (twice), (ii) 60% petrol/dichloromethane, (iii) 80% petrol/dichloromethane! and recrystallised from ethanol to give yellow crystals.

Yield 0.90 g (24%); mesomorphic behaviour (°C.) K 77.8 S_(A) * 99.6 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.15-1.55(23H, m), 1.40(3H, d),                1.55-1.75(1H, m), 1.75-1.90(2H, m), 4.00(2H, t),                4.55(1H, m), 7.00(2H, d), 7.05(1H, d), 7.55(6H,                3d), 7.65(1H, dd), 7.95(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1535, 1360; 1250;     MS (m/z)   583 M.sup.+ !, 471, 331, 71;     OR          α!.sub.D.sup.22° -1.2°(c=0.01,                CHCl.sub.3).     ______________________________________

2,3-Dimethoxy-6-nitrophenol (80)

2,3-Dimethoxyphenol (79) (5.00 g, 0.032 mol) was dissolved in glacial acetic acid (50 ml) and the resultant, stirred solution was cooled to 5° C. A cooled (5° C.) mixture of concentrated nitric acid (10 ml) and water (10 ml) was added in one portion to the phenol solution which immediately turned dark red-brown. The mixture was stirred for a further minute and poured into water (200 ml), this solution was neutralised with saturated sodium bicarbonate solution until all effervescense had ceased. The resultant yellow solution was extracted with several portions of diethyl ether until the ether remained almost colourless. The combined extracts were washed with water until the water remained almost colourless, dried (MgSO₄) and the ether evaporated off in vacuo to leave a brown oil. This was purified by column chromatography (10% petrol/dichloromethane) to give a bright yellow solid.

Yield 2.50 g (66%); mp 94°-97° C.

    ______________________________________     .sup.1 H NMR (CHCl.sub.3) δ                3.95(3H, s), 4.00(3H, s), 6.60(1H, d), 7.95(1H, d),                no obvious OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                3700-3000, 1530, 1360, 1240;     MS (m/z)   199 M.sup.+ !, 182, 139, 109, 95, 80.     ______________________________________

(R)-(-)-1,2-Dimethoxy-3-(1-methylheptyloxy)-4-nitrobenzene (81)

Quantities: compound 80 (1.39 g, 6.98 mmol), (S)-(+)-octan-2-ol (0.91 g, 6.98 mmol), DEAD (1.22 g, 6.98 mmol), triphenylphosphine (1.83 g, 6.98 mmol).

The experimental procedure was as described for the preparation of compound 5. The crude product was purified by column chromatography (10% petrol/dichloromethane) to give a pale yellow oil.

Yield 1.99 g (92%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.85(3H, t), 1.15-1.50(11H, m), 1.25(3H, d), 1.50-                1.70(1H, m), 1.70-1.85(1H, m), 3.85(3H, s),                3.95(3H, s), 4.50(1H, m), 6.70(2H, d), 7.65(2H, d);     IR (neat) ν.sub.max /cm.sup.-1                1520, 1345, 1290;     MS (m/z)   311 M.sup.+ !, 199, 182, 43;     OR          α!.sub.D.sup.25° +34.1°(c=0.01,                CHCl.sub.3).     ______________________________________

4-Bromo-2,3-dimethoxy-6-nitrophenol (82)

Quantities: compound 80 (1.00 g, 5.03 mmol), bromine (0.80 g, 5.03 mmol), chloroform (20 ml).

The experimental procedure was as described for the preparation of compound 41 except only one portion of bromine was used. The crude, oily product was purified by column chromatography (10% petrol/dichloromethane) to give a bright yellow solid.

Yield 1.49 g (100%); mp 77°-80° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                3.95(3H, s), 4.10(3H, s), 8.15(1H, s), 10.8(1H, s);     IR (KBr) ν.sub.max /cm.sup.-1                1525, 1330;     MS (m/z)   279 M.sup.+ !, 277 M.sup.+ !, 262, 260, 219, 217,     ______________________________________                53.

(R)-(-)-1-Bromo-2,3-dimethoxy-4-(1-methylheptyloxy)-5-nitrobenzene (83)

Quantities: compound 82 (2.00 g, 7.19 mmol), (S)-(+)-octan-2-ol (0.94 g, 7.19 mmol), DEAD (125 g, 7.19 mml), triphenylphosphine (1.89 g, 7.19 mmol).

The experimental procedure was as described for the preparation of compound 5. Purification by column chromatography (10% petrol/dichloromethane) gave a pale yellow oil.

Yield 2.74 g (98%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.25(3H, d), 1.10-1.50(8H, m), 1.50-                1.85(2H, 2m), 3.90(3H, s), 4.00(3H, s), 4.50(1H,                m), 7.80(1H, s);     IR (neat) ν.sub.max /cm.sup.-1                1535, 1350, 1265;     MS (m/z)   391 M.sup.+ !, 389 M.sup.+ !, 279, 277, 261, 259;     OR          α!.sub.D.sup.22° +6.9°(c=0.05,                CHCl.sub.3).     ______________________________________

(R)-(-)-4"-Decyloxy-2,3-dimethoxy-4-(1-methylheptyloxy)-5-nitroterphenyl (84)

Quantities: compound 83 (1.50 g, 3.85 mmol), compound 69 (2.20 g, 6.21 mmol), aqueous sodium carbonate (2M, 20 ml), tetrakis(triphenylphosphine)palladium(0) (0.30 g, 0.26 mmol), dimethoxyethane (100 ml).

The experimental procedure was as described for the preparation of compound 70. Purification was by column chromatography (50% petrol/dichloromethane) and recrystallisation from ethanol and ethyl acetate to give a pale yellow powder.

Yield 0.5 g (21%); mp 39°-40° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.15-1.90(29H, m), 3.80(3H, s),                3.95(3H, s), 4.00(2H, t), 4.55(1H, m), 7.00(2H, d),                7.50-7.65(6H, 3d), 7.65(1H, s);     IR (KBr) ν.sub.max /cm.sup.-1                1520, 1340, 1255;     MS (m/z)   619 M.sup.+ !, 507, 367, 71;     OR          α!.sub.D.sup.25° +13.2°(c=0.01,                CHCl.sub.3).     ______________________________________

1-Bromo-4-decyloxybenzene (86)

Quantities: 4-bromophenol 85 (10.00 g, 0.058 mol), 1-bromooctane (15.98 g, 0.072 mol), anhydrous potassium carbonate (39.94 g, 0.289 mol), potassium iodide (trace), butanone (250 ml).

The experimental procedure was as described for the preparation of compound 57. The crude product was distilled in vacuo (0.01 mmHg) to remove excess 1-bromooctane and purified by column chromatography (50% petrol/dichloromethane) to yield a colourless oil.

Yield 13.59 g (75%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                 0.90(3H, t), 1.20-1.55(14H, m), 1.75(2H, m),                 3.90(2H, t), 6.75(2H, d), 7.35(2H, d);     IR (neat) ν.sub.max /cm.sup.-1                 1240;     MS (m/z)    314 M.sup.+ !, 312 M.sup.+ !.     ______________________________________

4-Decyloxyphenylboronic acid (87)

Quantities: compound 86 (10.00 g, 0.032 mol), n-butyllithium (2.5M, 15.3 ml, 0.038 mol), trimethyl borate (6.64 g, 0.064 mol).

The experimental procedure was as described for the preparation of compound 47 to give a white solid.

Yield 7.68 g (86%); mp 61°-63° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.85(3H, t), 1.15-1.50(14H, m), 1.70(2H, m),                3.95(2H, t), 6.85(2H, d), 7.70(2H, d), 7.80(2H, s);     IR (KBr) ν.sub.max /cm.sup.-1                3700-3100, 1250;     MS (m/z)   278 M.sup.+ !, 110, 94.     ______________________________________

(R)-(-)-3-Cyano-4'-Decyloxy-4-(1-methylheptyloxy)biphenyl (88)

Quantities: compound 42 (1.50 g, 4.84 mmol), compound 87 (1.61 g, 5.81 mmol), aqueous sodium carbonate (2M, 20 ml), tetrakis(triphenylphosphine)palladium(0) (0.28 g, 0.24 mmol),1,2-dimethoxyethane (100 ml).

The experimental procedure was as described for the preparation of compound 70. The crude product was purified by column chromatography (40% petrol/dichloromethane) to give a viscous, colourless oil which was heated (150° C.) in vacuo (0.01 mmHg) until no more starting material distilled off.

Yield 0.86 g (50%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.35(3H, d), 1.15-1.95(26H, m),                4.00(2H, t), 4.50(1H, m), 6.85(1H, d), 6.95(2H, d),                7.40(2H, d), 7.60(1H, dd), 7.70(1H, d);     IR (neat) ν.sub.max /cm.sup.-1                2215, 1245;     MS (m/z)   463 M.sup.+ !, 351, 211, 71;     OR          α!.sub.D.sup.22° -24.4°(c=0.05,                CHCl.sub.3).     ______________________________________

(R)-(-)-4'-Decyloxy-4-(1-methylheptyloxy)-3-nitrobiphenyl (89)

Quantities: compound 66 (1.50 g, 4.55 mmol), compound 87 (1.52 g, 5.45 mmol), aqueous sodium carbonate (2M, 20 ml), tetrakis(triphenylphosphine)palladium(0) (0.26 g, 0.23 mmol), dimethoxyethane (100 ml).

The experimental procedure was as described for the preparation of compound 70. The crude product was purified by column chromatography (50% petrol/dichloromethane) to give a viscous, yellow oil which was heated (150° C.) in vacuo (0.01 mmHg) to remove any excess starting material.

Yield 1.12 g (51%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.40(3H, d), 1.20-1.90(26H, m),                4.00(2H, t), 4.50(1H, m), 6.95(2H, d), 7.10(1H, d),                7.45(2H, d), 7.65(1H, dd), 7.95(1H, d);     IR (neat) ν.sub.max /cm.sup.-1                1530, 1350, 1260, 1240;     MS (m/z)   483 M.sup.+ !, 372, 231, 71, 57;     OR          α!.sub.D.sup.22° -9.1°(c=0.03,                CHCl.sub.3).     ______________________________________

(R)-(-)-Octyl 4- 4-(1-methylheptyloxy)-3-nitrobenzoyloxy!benzoate (90)

Quantities: compound 16 (1.68 g, 5.69 mmol), compound 23 (1.42 g, 5.69 mmol), DCC (1.41 g, 6.83 mmol), DMAP (0.08 g, 0.63 mmol), dichloromethane (50 ml).

The experimental procedure was as described for the preparation of compound 17. The crude product was purified by column chromatography (50% petrol/dichloromethane) to give a pale yellow oil which was heated (150° C.) in vacuo (0.01 mmHg) to remove any starting material.

Yield 1.50 g (50%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.15-1.95(22H, m), 1.40(3H, d),                4.35(2H, t), 4.65(1H, m), 7.15(1H, d), 7.30(2H, d),                8.15(2H, d), 8.30(1H, dd), 8.60(1H, d);     IR (neat) ν.sub.max /cm.sup.-1                1740, 1715, 1530, 1355, 1235;     MS (m/z)   527 M.sup.+ !, 277, 167;     OR          α!.sub.D.sup.21° -6.4°(c=0.02,                CHCl.sub.3).     ______________________________________

(R)-(-)-Decyl 4- 4-(1-methylheptyloxy)-3-nitrobenzoyloxy!benzoate (91)

Quantities: compound 16 (1.59 g, 5.41 mmol), compound 24 (1.50 g, 5.41 mmol), DCC (1.34 g, 6.49 mmol), DMAP (0.07 g, 0.59 mmol), dichloromethane (50 ml).

The experimental procedure was as described for the preparation of compound 17 and purified as described for compound 90 to give a viscous, pale yellow oil.

Yield 1.68 g (56%).

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.45(3H, d), 1.15-1.95(26H, m),                4.35(2H, t), 4.65(1H, m), 7.15(1H, d), 7.30(2H, d),                8.15(2H, d), 8.30(1H, dd), 8.60(1H, d);     IR (neat) ν.sub.max /cm.sup.-1                1740, 1715, 1530, 1355, 1235;     MS (m/z)   555 M.sup.+ !, 278, 166, 120, 57, 43;     OR          α!.sub.D.sup.22.5° -7.8°(c=0.02,                CHCl.sub.3).     ______________________________________

Ethyl 3-nitro-4-octyloxybenzoate (92)

Quantities: Ethyl 4-hydroxy-3-nitrobenzoate (10) (5.00 g, 0.037 mol), 1-bromooctane (14.39 g, 0.075 mol), anhydrous potassium carbonate (15.45 g, 0.118 mol) potassium iodide (trace), butanone (200 ml).

The experimental procedure was as described for the preparation of compound 57. The crude product was purified by column chromatography (50% petrol/dichloromethane) to yield a pale yellow oil.

Yield 7.30 g (61%).

    ______________________________________     .sup.1 H NMR(CDCl.sub.3) δ                0.90(6H, 2t), 1.15-1.55(10H, m), 1.80-1.95(2H,                m), 4.15(2H, t), 4.40(2H, q), 7.10(1H, d), 8.20(1H,                dd), 8.50(1H, d);     IR (neat) ν.sub.max /cm.sup.-1                1720, 1530, 1360, 1240;     MS (m/z)   323 M.sup.+ !, 278, 212, 183, 166, 112.     ______________________________________

3-Nitro-4-octyloxybenzoic acid (93)

Quantities: compound 92 (3.50 g, 0.011 mol), sodium hydroxide (0.88 g, 0.022 mol), ethanol (80 ml), water (20 ml).

The experimental procedure was as described for the preparation of compound 9. During the reaction the solution changed colour from yellow to orange, on acidification a pale yellow solid was formed which was recrystallised from ethanol to give yellow crystals.

Yield 2.04 g (63%); mp 98°-100° C.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(3H, t), 1.15-1.55(10H, m), 1.85(2H, m),                4.20(2H, t), 7.15(1H, d), 8.25(1H, dd), 8.55(1H, d),                no obvious OH absorption;     IR (KBr) ν.sub.max /cm.sup.-1                3400-2400, 1695, 1530, 1350, 1250, 915, 830, 765;     MS (m/z)   295 M.sup.+ !, 183, 112, 83, 70.     ______________________________________

Octyl 4'-(4-octyloxy-3-nitrobenzoyloxy)-4-biphenylcarboxylate (94)

Quantities: compound 93 (1.60 g, 5.42 mmol), compound 6 (1.77 g, 5.42 mmol), DCC (1.34 g, 6.50 mmol), DMAP (0.07 g, 0.60 mmol).

The experimental procedure was as described for the preparation of compound 17. The crude product was purified by column chromatography (10% petrol/dichloromethane) and recrystallised from ethanol and ethyl acetate to give a pale yellow solid.

Yield 1.72 g (53%); mesomorphic behaviour (°C.) K 54.2 S_(C) 122.2 S_(A) 158.2 I.

    ______________________________________     .sup.1 H NMR (CDCl.sub.3) δ                0.90(6H, 2t), 1.20-1.60(20H, m), 1.70-1.95(4H,                2m), 4.20(2H, t), 4.35(2H, t), 7.20(1H, d), 7.30(2H,                d), 7.65(4H, 2d), 8.10(2H, d), 8.35(1H, dd),                8.70(1H, d);     IR (KBr) ν.sub.max /cm.sup.-1                1735, 1690, 1540, 1360, 1240;     MS (m/z)   603 M.sup.+ !, 278, 166.     ______________________________________

As shown in FIGS. 19A and 19B a spatial light modulator comprises a liquid crystal cell 1 formed by typically two glass walls 2, 3 and a 0.1-10 μm eg 2.5 μm thick spacer 4. The inner faces of the walls carry thin transparent indium tin oxide electrodes 5, 6 connected to a variable voltage source 7. On top of the electrodes 5, 6 are surface alignment layers 8, 9 eg of rubbed polyimide described in more detail later. Other alignment techniques are also suitable eg non-rubbing techniques such as evaporation of SiO₂. A layer 10 of liquid crystal material is contained between the walls 2, 3 and spacer 4. In front of the cell 1 is a linear polariser 11; behind the cell 1 is a quarter plate 12 (this may be optional) and a mirror 13. An example of a linear polariser is a polarising beam splitter (not illustrated here).

The alignment layers 8, 9 have two functions one to align contacting liquid crystals molecules in a preferred direction and the other to give a tilt to these molecules--a so called surface tilt--of a few degrees typically around 4° or 5°. The alignment layers 8, 9 may be formed by placing a few drops of the polyimide onto the cell wall and spinning the wall until a uniform thickness is obtained. The polyimide is then cured by heating to a predetermined temperature for a predetermined time followed by unidirectional rubbing with a roller coated with a cloth, eg a nylon cloth.

There are a variety of electroclinic devices in which the compounds of the present invention may be incorporated. For example in the above description of FIGS. 19A and 19B, active back plane driving may be utilised. One of the walls forming the cell may be formed from a silicon substrate eg a wafer which possesses circuitry, which may or may not contain mirrored electrodes, for driving pixels.

For many of these devices there exists an optimum thickness for the cell which is related to the birefringence (Δn) given by: ##EQU1## wherein: λ=wavelength of operation

Δn=birefringence of liquid crystalline material

m=integer.

Small arrays of pixels may be driven by applying dc voltages to each individual pixel, where the applied voltage induces a relative tilt, thereby setting the grey level or phase modulation. It is desirable to maintain a substantially zero net dc so the inverse image can be applied for the same time period to neutralise charging effects.

Some suitable methods for driving electroclinic devices containing arrays of pixels described by the present invention may be found in UK patent application GB 2 247 972 A.

Suitable methods for driving electroclinic devices may benefit by including in such devices, materials which possess a high resistivity and a large optical response.

It may also be advantageous that the liquid crystal material possesses a high resistivity, one reason being in order to minimise leakage current through the pixel whilst the pixel is being addressed. Some addressing schemes which incorporate active backplanes rely on this charge storage to maintain their pre-determined level.

The mode of operation of the devices described by the current invention includes either amplitude modulation or phase modulation. Similarly, devices may be used in reflectance or transmissive mode.

The following compounds are example compounds that have been synthesised for the present invention. Inukai et al have described the synthesis of some of these type molecules in Ferroelectrics, 1988, vol. 85, 451-59.

In the synthetic experimental section, materials 1, 25, 56 and 67 were purchased from Merck Ltd, Poole and materials 7, 10, 19, 29, 34, 38, 51, 61, 64, 79 and 85 were purchased from Aldrich.

EXAMPLE 1 ##STR6## EXAMPLE 2 ##STR7## EXAMPLE 3 ##STR8## EXAMPLE 4 ##STR9## EXAMPLE 5 ##STR10## EXAMPLE 6 ##STR11## EXAMPLE 7 ##STR12## EXAMPLE 8 ##STR13## EXAMPLE 9 ##STR14## EXAMPLE 10 ##STR15## EXAMPLE 11 ##STR16## EXAMPLE 12 ##STR17## EXAMPLE 13 ##STR18## EXAMPLE 14 ##STR19## EXAMPLE 15 ##STR20## EXAMPLE 16 ##STR21## EXAMPLE 17 ##STR22## EXAMPLE 18 ##STR23## EXAMPLE 19 ##STR24## EXAMPLE 20 ##STR25## EXAMPLE 21 ##STR26## EXAMPLE 22 ##STR27## EXAMPLE 23 ##STR28## EXAMPLE 24 ##STR29## EXAMPLE 25 ##STR30##

Table 1 illustrates the phase transition temperatures for the compounds of Formula I.

Tables 2-4 show the effect of temperature on spontaneous polarisation (Ps) for example compounds 18, 60 and 46.

                  TABLE 1     ______________________________________     Compound       Phase Transition Temperature/°C.     ______________________________________     17             K 85.0 (S.sub.c * 71.7) S.sub.A * 126.8 I     18             K 37.0 S.sub.c * 56.4 S.sub.A * 62.5 I      18a           K 45.1 S.sub.c * 49.5 S.sub.A * 58.7 I      18b           K 36.2 S.sub.c * 59.2 S.sub.A * 67.6 I     28             K 67.0 (S.sub.c * 62.0) S.sub.A * 132.9 I     32             K 39-140 I     33             K 57.4 S.sub.c * 64.4 N * 69.7 I     37             K 61.2 S.sub.c * 71.7 I     45             K 126.5 S.sub.A * 133.3 I     46             K ? S.sub.c * 52.1 S.sub.A * 64.5 I     55             K 60.5 (S.sub.c * 58.7) S.sub.A * 68.1 I     59             K 94.2 S.sub.c * 112.7 S.sub.A * 168.7 I     60             K 64.9 S.sub.c * 100.2 S.sub.A * 118.8 I     70             K 65.3 (S.sub.c * 60.0) S.sub.A * 100.1 I     71             K 71.8 S.sub.A * 153.8 I     72             K 46.7 S.sub.c * 53.5 S.sub.A * 96.0 I     75             K 63.5 S.sub.c * 104.1 S.sub.A * 152.6 I     76             K 60.3 S.sub.A * 105.6 I     77             K 60.0 S.sub.c * 90.1 S.sub.A * 144.2 I     78             K 77.8 S.sub.A * 99.6 I     84             K 39-40 I     94             K 54.2 S.sub.c  122.2 S.sub.A  158.2 I     97             K 41 I     ______________________________________

It is understood that where the above compounds are optically active, an optically inactive phase can be provided by the same method of synthesis using an optically inactive racemic isomer mixture as starting material. Material 55 has a monotropic C* phase.

                  TABLE 2     ______________________________________     Compound 18            Temp/°C.                   Ps nC/cm.sup.2     ______________________________________            54     226            50     336            44     405            40     451            34     498            30     525            24     550     ______________________________________

                  TABLE 3     ______________________________________     Compound 60            Temp/°C.                   Ps nC/cm.sup.2     ______________________________________            84     370            74     440            64     480     ______________________________________

                  TABLE 4     ______________________________________     Compound 46            Temp/°C.                   Ps nC/cm.sup.2     ______________________________________            46      65            45      90            44     115            43     135            42     138     ______________________________________

Ps measurements were made using a Diamant bridge and approximately 6 μm cells that had parallel polyimide alignment.

Compound 70 has a Ps of 230 nC/cm² measured approximately 2° C. into the S_(C) * phase.

Compound 45 has a Ps value of approximately 7 nC/cm² at 85° C. This lower value of Ps may be due to the fact that the neighbouring terminal chain results in less steric hindrance with the CN group. It may also be due to the fact that the chiral centre has been moved further away from the core of the molecule.

Compounds 18 and 46 are the same structurally, apart from the fact that there is a CN substituent on compound 46 and a nitro group on compound 18. Replacing the NO₂ with the CN group has resulted in a decreased value for Ps and the S_(C) * phase stability is less in the CN containing molecule.

Compound 55 has a Ps of 367 nC/cm² at 10° C. below the A-C* transition.

The S_(C) * phase which exists below the S_(A) * phase in some of the compounds is advantageous because it allows the formulation of electroclinic mixtures having a S_(C) * phase near to this operating temperature range. This S_(C) * phase can allow lower voltage operation and/or larger induced tilt angles than could otherwise be attained. A further use of the S_(C) * is to provide means for characterising the materials according to the magnitude of their spontaneous polarisation in the S_(C) * phase.

It is also possible that the desirable properties outlined earlier in this description can be enhanced at the S_(C) *-S_(A) * transition point thus resulting in a broader working temperature range. Furthermore, devices using materials of Formula I having a S_(C) *-S_(A) * phase sequence may provide both linear or bistable response eg modulation of the temperature of the device.

Graphs of induced tilt versus voltage are illustrated in FIGS. 20-22 for example compounds 18, 60 and 70.

In FIG. 20, Induced tilt/° versus Voltage/V is shown at three different temperatures in a 1.8 μm cell for compound 18.

In FIG. 21, Induced tilt/° versus Voltage/V is shown at four different temperatures in a 2 μm cell for compound 60.

In FIG. 22, Induced tilt/° versus Voltage/V is shown at seven different temperatures in a 1.4 μm cell for compound 70.

Induced tilt values of up to 17° at 62° C. using approximately 15V/μm have been measured for the material illustrated in FIG. 22.

10% of compound 18 was mixed with compound 94.

This resulted in the following phase transitions:

    K50.0S.sub.C * 114.0 S.sub.A * 146.0 I

Ps=16.8 nC cm⁻² at (T_(A) *-_(C) *-10° C).

Ps measurements were also made on compounds which had been mixed with the following 1:1:1 mixture H1: ##STR31## 5% of the following compound mixed with H1 resulted in a Ps of 1.3 nC/cm² at T_(C) *-_(A) *-10° C. ##STR32## 5% of the following compound mixed with H1 resulted in a Ps of 4.0 nC/cm² at T_(C) *-_(A) *-10° C. ##STR33##

Suitable devices which the materials of the present invention may be incorporated in include beam steerers, piezoelectric actuators or sensors and pyroelectric sensors and displays in general.

The materials of the present invention may also be useful as dopants in ferroelectrics.

The materials of the current invention may be mixed together and/or with other liquid crystal compounds.

The materials of the present invention may also be useful as second order non-linear optic materials for second harmonic conversion of light eg conversion of infra-red semi-conductor diode laser to the blue/green region of the spectrum, or the linear electro-optic modulation of light by the Pockels effect. These applications normally require a tilted chiral smectic phase such as S_(C) *, S_(F) *, S_(J) * to be present.

Typically such materials may be incorporated into devices comprising two spaced cell walls which are treated on at least one facing surface with an alignment layer. Between the cell walls is a layer of smectic liquid crystal material. There may or may not be electrodes present.

These devices may require electrodes for the application of electric field(s) either perpendicular to, or parallel to the cell normal, this may, for example, aid alignment of the S_(C) * material in the device or enable electro-optic modulation. The electrodes may be located on the cell walls and/or within the liquid crystal material itself. 

We claim:
 1. An electroclinic device comprising two spaced cell walls each bearing electrode structures and treated on at least one facing surface with an alignment layer, a layer of a smectic liquid crystal material enclosed between the cell walls, wherein the liquid crystal material contains one or more of the compounds described by formula I: ##STR34## wherein X is CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy;X₂ is CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy; X₃ is CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy or hydrogen; X₄ is CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy or hydrogen;provided that at least one of X or X₂ is CF₃, CF₂ H, CFH₂, CN, NO₂ or halogen; A and B are independently phenyl, mono-fluorinated phenyl, di-fluorinated phenyl or cyclohexyl; Y is a single bond or COO or OOC or C.tbd.C; q is 0 or 1; R₁ is an end group of Formula II: ##STR35## wherein Z is a single bond or O or CO₂ or (CH₂)_(n) or CH₂)_(n) O where n may be 1 or 2; J and M are independently selected from H and C₁₋₄ alkyl; W is C₁ -C₁₂ straight or branched alkyl chain; and R₂ contains 1-14 carbon atoms wherein one or more non-adjacent CH₂ groups may be replaced by CO₂ or O;and when at least one of X or X₂ is halogen then q is 1 and Y is not a single bond and the compound of Formula I possesses a chiral center.
 2. A device containing liquid crystal material according to claim 1 wherein in the liquid crystal material:W is C₁ -C₈ straight chain alkyl, Z is 0 or CH₂ O, M and J and independently chosen from H or methyl or ethyl; R₂ contains 5-12 carbon atoms wherein one of the CH₂ groups may be replaced by CO₂ or O; q=1; A and B are phenyl; Y is CO₂ or a single bond.
 3. A device containing liquid crystal material according to claim 2 wherein in the liquid crystal material:X₃ =X₄ =H, one of X or X₂ is CN, NO₂, halogen or CF₃ and the other is H.
 4. A device of claim 1 wherein the liquid crystal has a formula ##STR36## wherein X is CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy;X₂ is CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy; X₃ is CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy, hydrogen; X₄ is CN, NO₂, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy, hydrogen;provided that at least one of X or X₂ is CF₃, CF₂ H, CFH₂, CN, NO₂ or halogen; A and B are independently phenyl, mono-fluorinated phenyl, di-fluorinated phenyl or cyclohexyl; Y is a single bond or COO or OOC or C.tbd.C; R₁ is an end group of Formula II: ##STR37## wherein Z is a single bond, O, CO₂, (CH₂)_(n) or (CH₂)_(n) O where n may be 1 or 2; J and M are independently selected from H and C₁₋₄ alkyl; W is C₁ -C₁₂ straight or branched alkyl chain; and R₂ contains 1-14 carbon atoms wherein one or more non-adjacent CH₂ groups may be replaced by CO₂ or O.
 5. A non-linear optic device comprising two spaced cell walls, treated on at least one facing surface with an alignment layer, a layer of a smectic liquid crystal material enclosed between the cell walls, wherein the liquid crystal material contains one or more compounds of Formula I: ##STR38## wherein X is CN, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy;X₂ is CN, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy; X₃ is CN, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy or hydrogen; X₄ is CN, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy or hydrogen;provided that at least one of X or X₂ is CF₃, CF₂ H, CFH₂, CN, or halogen; A and B are independently phenyl, mono-fluorinated phenyl, di-fluorinated phenyl or cyclohexyl; Y is a single bond or COO or OOC or C.tbd.C; q is 0 or 1; R₁ is an end group of formula II: ##STR39## wherein Z is a single bond or O or CO₂ or (CH₂)_(n) or (CH₂)_(n) O where n may be 1 or 2; J and M are independently selected from H and C₁₋₄ alkyl; W is C₁ -C₁₂ straight or branched alkyl chain; R₂ contains 1-14 carbon atoms wherein one or more non-adjacent CH₂ groups may be replaced by CO₂ or O;and further provided that at least one of the following criteria is met: (i) q=0; (ii) Y is C.tbd.C; and (iii) X, X₂, X₃, and X₄ are selected from CF₃, CF₂ H, CFH₂, CN, halogen, alkyl or alkoxy such that any one of the following substitution patterns may be present:(iv) X (v) X₂ (vi) X₂ and X (vii) X and X₃ (viii) X₂ and X₄ (ix) X and X₃ and X₄ or X and X₂ and X₄.
 6. A device according to claim 1 wherein the device further comprises at least two electrode structures.
 7. A device according to claim 6 comprising means for applying an electric field parallel to the cell normal.
 8. A device according to claim 6 comprising means for applying an electric field perpendicular to the cell normal.
 9. A device of claim 5 wherein the liquid crystal has the formula ##STR40## wherein X is CN, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy;X₂ is CN, CF₃, CF₂ H, CFH₂, halogen, hydrogen, alkyl or alkoxy; X₃ is CN, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy, hydrogen; X₄ is CN, CF₃, CF₂ H, CFH₂, halogen, alkyl, alkoxy, hydrogen;provided that at least one of X or X₂ is CF₃, CF₂ H, CFH₂, CN, or halogen; A and B are independently phenyl, mono-fluorinated phenyl, di-fluorinated phenyl or cyclohexyl; Y is a single bond or COO or OOC or C.tbd.C; R₁ is an end group of Formula II: ##STR41## wherein Z is a single bond, O, CO₂, (CH₂)_(n) or (CH₂)_(n) O where n may be 1 or 2; J and M are independently selected from H and C₁₋₄ alkyl; W is C₁ -C₁₂ straight or branched alkyl chain; and R₂ contains 1-14 carbon atoms wherein one or more non-adjacent CH₂ groups may be replaced by CO₂ or O.
 10. A device according to claim 4 or claim 9 wherein the liquid crystal material has the formula: ##STR42## 